CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Ser. No. 09/695,194 filed on Oct. 24, 2000 now abandoned, which is a divisional of U.S. Ser. No. 09/262,378 filed Mar. 4, 1999, now U.S. Pat. No. 6,180,546 issued on Jan. 30, 2001, which is a continuation of U.S. Ser. No. 08/899,005 filed Jul. 23, 1997, now U.S. Pat. No. 5,994,247 issued on Nov. 30, 1999, which is a continuation of U.S. Ser. No. 08/535,587 filed Sep. 28, 1995, now abandoned, which is a continuation of U.S. Ser. No. 08/039,086, filed Apr. 9, 1993, now abandoned, which claims priority to International Application No. PCT/GB93/00085, filed Jan. 15, 1993, which claims priority to GB 92 00993.5, filed Jan. 17, 1992 and GB 92 24612.3, filed Nov. 24, 1992. 
    
    
     INTRODUCTION AND BACKGROUND 
     This invention relates to saline soluble, non-metallic, amorphous, inorganic oxide, refractory fibrous materials. 
     Inorganic fibrous materials are well known and widely used for many purposes (e.g. as thermal or acoustic insulation in bulk, mat, or blanket form, as vacuum-formed shapes, as vacuum formed boards and papers, and as ropes, yarns or textiles; as a reinforcing fibre for building materials; as a constituent of brake blocks for vehicles). In most of these applications the properties for which inorganic fibrous materials are used require resistance to heat, and often resistance to aggressive chemical environments. 
     Inorganic fibrous materials can be either glassy or crystalline. Asbestos is an inorganic fibrous material one form of which has been strongly implicated in respiratory disease. 
     It is still not clear what the causative mechanism is that relates some asbestos with disease but some researchers believe that the mechanism is mechanical and size related. Asbestos of a critical size can pierce cells in the body and so, through long and repeated cell injury, have a bad effect on health. 
     Whether this mechanism is true or not regulatory agencies have indicated a desire to categorise any inorganic fibre product that has a respiratory fraction as ‘hazardous’, regardless of whether there is any evidence to support such categorisation. Unfortunately for many of the applications for which inorganic fibres are used, there are no realistic substitutes. 
     Accordingly there is a demand for inorganic fibres that will pose as little risk as possible (if any) and for which there are objective grounds to believe them safe. 
     A line of study has proposed that if inorganic fibres were made that were sufficiently soluble in physiological fluids that their residence time in the human body was short; then damage would not occur or at least be minimised. As the risk of asbestos-linked disease appears to depend very much on the length of exposure this idea appears reasonable. Asbestos is extremely insoluble. 
     As intercellular fluid is saline in nature the importance of fibre solubility in saline solution has long been recognised. If fibres are soluble in physiological saline solution then, provided the dissolved components are not toxic, the fibres should be safer than fibres which are not so soluble. The shorter the time a fibre is resident in the body the less damage it can do. H. Forster in ‘The behaviour of mineral fibres in physiological solutions’ (Proceedings of 1982 WHO IARC Conference, Copenhagen, Volume 2, pages 27-55(1988)) discussed the behaviour of commercially produced mineral fibres in physiological saline solutions. Fibres of widely varying solubility were discussed. 
     International Patent Application No. WO87/05007 disclosed that fibres comprising magnesia, silica, calcia and less than 10 wt % alumina are soluble in saline solution. The solubilities of the fibres disclosed were in terms of parts per million of silicon (extracted from the silica-containing material of the fibre) present in a saline solution after 5 hours of exposure. The highest value revealed in the examples had a silicon level of 67 ppm. In contrast, and adjusted to the same regime of measurement, the highest level disclosed in the Förster paper was equivalent to approximately 1 ppm. Conversely if the highest value revealed in the International Patent Application was converted to the same measurement regime as the Förster paper it would have an extraction rate of 901,500 mg Si/kg fibre—i.e. some 69 times higher than any of the fibres Förster tested, and the fibres that had the highest extraction rate in the Förster test were glass fibres which had high alkali contents and so would have a low melting point. This is convincingly better performance even taking into account factors such as differences in test solutions and duration of experiment. 
     International Patent Application No. WO89/12032 disclosed additional fibres soluble in saline solution and discusses some of the constituents that may be present in such fibres. 
     European Patent Application No. 0399320 disclosed glass fibres having a high physiological solubility. 
     Further patent specifications disclosing selection of fibres for their saline solubility are European 0412878 and 0459897, French 2662687 and 2662688, PCT WO86/04807 and WO90/02713. 
     The refractoriness of the fibres disclosed in these various prior art documents varies considerable. The maximum service temperature of any of these disclosed fibres (when used as refractory insulation) is up to 815° C. (1500° F.). 
     Service temperature for refractory insulation is definable in many ways but to be consistent with the above mentioned International Patent Applications this application shall mean by service temperature that temperature at which the fibre shows acceptable shrinkage (maximum of 5% linear shrinkage after exposure to temperature for 24 hours) and at which the fibre has not appreciably suffered through excessive sintering or softening. 
     There is a demand for physiologically soluble fibres having a service temperature of greater than 815° C., particularly for such fibres having a service temperature above 900° C. 
     Testing for physiological solubility and safety can be done by inhalation studies on, e.g. rats. However such studies are extremely time consuming and costly. A study can take of the order of 2½ years from start and can easily cost 1 million pounds per study. A cheaper alternative is to test for solubility in physiological or like fluids in vitro. 
     Testing of an inorganic fibre for solubility in physiological solutions is not so time consuming, but there is currently no way of predicting which systems will produce such soluble fibres. Therefore anyone seeking to find such soluble fibres has to work on a trial and error basis assisted by what is commonly known as ‘chemical intuition’ but is equally commonly known as ‘a hunch’. Such trial and error testing is laborious and time consuming. Further, once a fibre is found that is soluble there is no guarantee that it will be usable at useful service temperatures. 
     Accordingly there is a demand for a method of predicting whether a fibre will have a reasonable solubility in physiological solutions, and further there is a demand that such a test should preferably give an indication as to expected service temperature. 
     Shrinkage of inorganic refractory fibres occurs through two mechanisms; the first is viscous flow of the fibre material. Most inorganic refractory fibres are glasses and so may be defined as liquids having an exceedingly high viscosity (but still liable to flow). By their nature fibres are elongate and so have a high surface area per unit volume. As the reduction of surface area is a means of reducing the surface energy of a material, when the glass becomes fluid enough it will flow so as to reduce surface area. This flow results in a coarsening and shortening of the fibres and so to shrinkage, and in the extreme results in disruption of the fibres into separate particles. 
     The second mechanism leading to shrinkage is that at elevated temperatures glasses may crystallise to form one or more crystal phases. Usually these crystal phases have a smaller molar volume than the glasses from which they crystallise and so shrinkage results. Some fibres are known for which the molar volume of the crystalline form exceeds that of the glass (for example Al 2 O 3 /SiO 2  glassy fibres may crystallise to form mullite crystals). In these cases the expansion due to crystallisation may oppose the shrinkage caused by viscous flow. 
     If shrinkage through viscous flow occurs at a much lower temperature than crystallisation then the crystallisation may not be able to compensate for such shrinkage. 
     There is a demand for a fibre in which both viscous flow and crystallisation occur at as high and as similar a temperature as possible, and preferably in which the expansion due to crystallisation closely matches the shrinkage due to viscous flow so that the net effect is as close to zero shrinkage as possible. 
     When used as refractory insulation inorganic refractory fibres are used in several forms. The fibres may be supplied as a bulk material, but in this form the fibres are difficult to handle for many applications. Alternatively the fibre may be supplied as a blanket. Blanket fibre is generally made by a process of sucking fibre from air onto a conveyor to form a blanket. Because the fibres tend to be aligned parallel to the conveyor surface they can separate easily. Accordingly the blanket fibres are secured together by adding a binder to lock the fibres together, or by needling the blanket, or both. In needling needles are passed through the thickness of the blanket to push and draw fibres to lie transverse to the blanket and so tie the fibres together. Because binders are usually resins, such as phenolic resins, they burn off on first firing. There is a desire to reduce the amount of such binders used both because of possible health implications in handling, and because the combustion products may affect the strength of the fibres. Thus needled blanket is usually preferred. 
     The fibres may also be supplied as blocks, generally made from assembled layers of inorganic fibre blanket. 
     For some fibres needling is not possible. Crystalline fibres are generally too brittle to stand the stresses involved. For the fibres known in the industry as glass fibres (which are generally used for low temperature applications) the amount of ‘shot’ (unfiberised glass particles) present is generally too high to allow needling as the shot damages the needles. There is no needled blanket on the market that has a maximum service temperature in the range 900° C.-1200° C. There are needled blankets having a higher maximum service temperature but these use expensive fibres in comparison with other fibres usable (with the aid of binders) as blanket in the temperature range 900° C.-1200° C. 
     Accordingly there is a demand for needled fibre blanket formed from inexpensive materials, being soluble in saline solutions, and having a maximum service temperature in the range 900° C.-1200° C. 
     As stated previously refractory oxide fibres are made by several methods all of which involve the formation of a melt of oxides and the subsequent fiberisation of the melt by e.g. spinning or blowing. 
     The melt of oxide material is often formed by electrical discharge melting of the constituent raw materials. The applicants, in manufacture of a CaO/MgO/SiO 2  refractory oxide fibre encountered problems due to the necessity of handling CaO. These problems were discovered to be due to the moisture content of CaO as commercially available. One of the problems of use of CaO is the outgasing that results upon melting and this led at the least to a porous melt pool which caused fluctuations in the melt current; in the extreme the outgasing was explosive. Additionally use of CaO appeared to cause accelerated attack on the melt electrodes. Also CaO is a difficult and corrosive material to handle. 
     Accordingly there is a need for a process that minimises the use of CaO. 
     Accordingly the present invention provides the following features both independently and in combination: 
     SUMMARY OF THE INVENTION 
     A. Use of a vitreous inorganic fibre in the knowledge that it has a composition meeting the criteria either: that the calculated sum of the free energies of hydration of the compounds that would or could be present at equilibrium (on the basis of knowledge, informed belief or reasonable assumption) is more negative than −10 kcal/100 grams (−418.4 kJ/kg) of composition; or that the percentage of non-bridging oxygens is more than 30%. Such compositions tend to be saline soluble. 
     B. Use of such a vitreous inorganic fibre in the knowledge that it has a composition meeting the criterion that the ratio of glass modifiers to network formers is less than a critical value (for SiO 2  based compositions the critical value is 1). Such compositions tend to be glass formers. 
     C. The invention also encompasses fibres selected by adopting such criteria as a test for solubility and glass formation. 
     D. Use as saline soluble fibres having a shrinkage of less than 3.5% when exposed to 1000° C. for 24 hours and/or 800° C. for 24 hours, of vitreous fibres having a composition comprising (in weight %): 
                                         SiO 2     &gt;58%   (for MgO =&lt; 10%) and       SiO 2     &gt;58% + 0.5(% MgO − 10)   (for MgO &gt;= 10%)       (SiO 2  preferably       being below 70%)       CaO    0%–42%       MgO    0%–31.33%       Al 2 O 3      0%–&lt;3.97%                    
and being essentially free of fluxing components such as alkali metals and boron oxide.
 
     E. In one such usage the first crystalline material resulting on crystallisation has the crystal structure of diopside and has the composition consisting essentially of:— 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Composition A 
               
               
                   
                 Component 
                 Weight percent 
               
               
                   
                   
               
             
             
               
                   
                 SiO 2   
                 59–64 
               
               
                   
                 Al 2 O 3   
                   0–3.5 
               
               
                   
                 CaO 
                 19–23 
               
               
                   
                 MgO 
                 14–17 
               
               
                   
                   
               
             
          
         
       
     
     F. In a second such usage the first crystalline material resulting on crystallisation has the crystal structure of wollastonite/pseudowollastonite and has the composition consisting essentially of:— 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Composition B 
               
               
                   
                 Component 
                 Weight percent 
               
               
                   
                   
               
             
             
               
                   
                 SiO 2   
                 60–67 
               
               
                   
                 Al 2 O 3   
                   0–3.5 
               
               
                   
                 CaO 
                 26–35 
               
               
                   
                 MgO 
                 4–6 
               
               
                   
                   
               
             
          
         
       
     
     G. The fibres used in such manner may further be used as needled blankets. 
     H. Preferably the fibres of the general composition and compositions A and B mentioned above have a SiO 2  content (expressed as a weight percentage of the constituents SiO 2 , CaO and MgO) of greater than 60%. 
     I. The present invention further provides a method for the manufacture of refractory oxide fibres containing calcium and silicon by the formation of an oxide melt containing calcium and silicon characterised in that all or part of the calcium and all or part of silicon is provided by a calcium silicate. 
    
    
     
       BRIEF DESCRIOTION OF THE DRAWINGS 
       The invention is illustrated by way of example in the following description and with reference to the drawings in which:— 
         FIG. 1  is a three-axis phase diagram indicating the crystalline phases in the system SiO 2 /CaO/MgO ( Phase Diagrams for Ceramists , The American Ceramic Society, 1964) a key to this diagram is at the end of the specification; 
         FIG. 2  is a three-axis composition plot of the projection onto the SiO 2 /CaO/MgO phase field of compositions comprising SiO 2 , CaO, MgO and Al 2 O 3 ; 
         FIG. 3  is a temperature/time plot of the firing regime used in a series of cyclic exposure tests of experimental compositions; 
         FIG. 4  is a plot of log (total solubility) v calculated free energy of hydration for a series of fibres. 
         FIG. 5  is a plot of log (total solubility) v % non-bonding oxygens for a series of fibres (see below). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A series of fibres were made of the compositions shown in Table 1. These fibres were melt spun by using a vertical spinning system of the type known for making inorganic fibres. Also shown in Table 1 are the compositions of some comparative commercially available inorganic oxide fibres and glass fibres. 
     
       
         
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Al 2 O 3   
                 SiO 2   
                 CaO 
                 MgO 
                 ZrO 2   
                 MST 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 SW-A 
                 3.3 
                 59.3 
                 20.5 
                 15.5 
                 — 
                   
               
               
                 SW-A1 
                 1.1 
                 63.7 
                 20.5 
                 15.2 
                 — 
               
               
                 SW-A2 
                 0.8 
                 60.8 
                 21.4 
                 15.4 
                 — 
               
               
                 SW-B1 
                 2.3 
                 65.3 
                 26.8 
                 5.7 
                 — 
               
               
                 SW-B2 
                 1.3 
                 66.9 
                 27.5 
                 5.2 
                 — 
               
               
                 SW-B3 
                 1.0 
                 60.0 
                 34.0 
                 4.4 
                 — 
               
             
          
           
               
                 COMPARATIVE EXAMPLES 
               
             
          
           
               
                 CRBT 
                 46.5 
                 53 
                 0.04 
                 0.01 
                 — 
                 1260° C. 
               
               
                 CWBT 
                 40.6 
                 49.5 
                 5.50 
                 4.00 
                 — 
                  870° C. 
               
               
                 CHBT 
                 49.7 
                 35.1 
                 0.04 
                 0.01 
                 14.7 
                 1425° C. 
               
               
                 Glass 
                 15.2/ 
                 53.7/ 
                 21.1/ 
                 1.3/ 
                 — — 
                 +5.9–6.2% B 2 O 3   
               
               
                 Fibre 
                 15.5 
                 57.5 
                 21.8 
                 1.6 
                   
                 0.11–0.12% TiO 2   
               
               
                   
                   
                   
                   
                   
                   
                 0.46% Na 2 O 
               
               
                   
                   
                   
                   
                   
                   
                 0.32–0.33% K 2 O 
               
               
                 Needled 
                 3.7 
                 60.5/ 
                 8.1 
                 4.0 
                 — — 
                 +2.85–2.95% B 2 O 3   
               
               
                 Glass 
                   
                 60.0 
                 7.9 
                   
                 — 
                 13.5% Na 2 O 
               
               
                 Fibre 
                   
                   
                   
                   
                   
                 1.0% K 2 O 
               
               
                   
               
               
                 [MST = Maximum Service Temperature (oxidising atmosphere)] 
               
             
          
         
       
     
     The fibres SW-A, SW-A1, SW-A2, SW-B1, SW-B2 and SW-B3 were tested for solubility by the following method. 
     The fibre was first chopped in the following manner. 2.5 g of fibre (deshotted by hand) was liquidised with 250 cm 3  of distilled water in a domestic Moulinex (Trade Mark) food blender for 20 seconds. The suspension was then transferred to a 500 cm 3  plastic beaker and allowed to settle after which as much liquid as possible was decanted and the remaining liquid removed by drying in an oven at 110° C. 
     The solubility test apparatus comprised a shaking incubator water bath, and the test solution had the following composition:— 
                                                 Compound   Name   Grams                           NaCl   Sodium chloride   6.780           NH 4 Cl   Ammonium chloride   0.540           NaHCO 3     Sodium bicarbonate   2.270           Na 2 HPO 4 •H 2 O   Disodium hydrogen   0.170               phosphate           Na 3 C 6 H 5 O 7P •2H 2 O   Sodium citrate   0.060               dihydrate           H 2 NCH 2 CO 2 H   Glycine   0.450           H 2 SO 4  s.g. 1.84   Sulphuric acid   0.050                        
The above materials were diluted to 1 litre with distilled water to form a physiological-like saline solution.
 
     0.500 grams±0.0003 grams of chopped fibre was weighed into a plastic centrifuge tube and 25 cm 3  of the above saline solution added. The fibre and saline solution was shaken well and inserted into the shaking incubator water bath maintained at body temperature (37° C.±1° C.). The shaker speed was set at 20 cycles/minute. 
     After the desired period (usually 5 hours or 24 hours) the centrifuge tube was removed and centrifuged at ≈4500 revs/minute for approximately 5 minutes. Supernatant liquid was then drawn off using a syringe and hypodermic needle. The needle was then removed from the syringe, air expelled from the syringe, and the liquid passed through a filter (0.45 micron cellulose nitrate membrane filter paper [WCN type from Whatman Labsales Limited]) into a clean plastic bottle. The liquid was then analysed by atomic absorption using a Thermo Jarrell Ash Smith-Hiefje II machine. 
     The operating conditions were:— 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                   
                   
                   
                   
                 FLAME 
               
               
                   
                   
                   
                   
                 (Nitrous 
               
               
                   
                 WAVELENGTH 
                 BAND 
                 CURRENT 
                 Oxide + 
               
               
                 ELEMENT 
                 (nm) 
                 WIDTH 
                 (MA) 
                 Acetylene) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 Al 
                 309.3 
                 1.0 
                 8 
                 Fuel Rich 
               
               
                 SiO 2   
                 251.6 
                 0.3 
                 12 
                 ″ 
               
               
                 CaO 
                 422.7 
                 1.0 
                 7 
                 Fuel Lean 
               
               
                 MgO 
                 285.2 
                 1.0 
                 3 
                 ″ 
               
               
                   
               
             
          
         
       
     
     The procedure and standards adopted for determining the above elements were as set out below 
     SiO 2  can be determined without dilution up to 250 ppm concentration (1 ppm=1 mg/Litre). Above this concentration an appropriate dilution was made volumetrically. A 0.1% KCl solution (0.1 g in 100 cm 3 ) was added to the final dilution to prevent ionic interference. NB If glass apparatus is used, prompt analysis is necessary. 
     From a stock solution of 1000 ppm pure ignited silica (99.999%) (fused with Na 2 CO 3  at 1200° C. for 20 minutes in a platinum crucible (0.2500 g SiO 2 /2 g Na 2 CO 3 ) and dissolved in dilute hydrochloric acid (4 molar) made up to 250 cm 3  with distilled water in a plastic volumetric flask) the following standards were produced:— 
     
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 STANDARD (PPM SiO 2 ) 
                 STOCK SOLUTION (cm 3 ) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10.0 
                 1.0 
               
               
                   
                 20.0 
                 2.0 
               
               
                   
                 30.0 
                 3.0 
               
               
                   
                 50.0 
                 5.0 
               
               
                   
                 100.0 
                 10.0 
               
               
                   
                 250.0 
                 25.0 
               
               
                   
                   
               
             
          
         
       
     
     Add 0.1% KCl to each standard before making to 100 cm 3 . 
     Aluminium may be measured directly from the sample without dilution. Standards of 1.0, 5.0 and 10.0 ppm Al may be used. For calibration readings are multiplied by 1.8895 to convert from A1 to Al 2 O 3 . 
     A standard Al atomic absorption solution (e.g. BDH 1000 ppm Al) was bought and diluted using an accurate pipette to the desired concentration. 0.1% KCl was added to prevent ionic interference. 
     Calcium may require dilutions on the sample before determination can be carried out (i.e. ×10 and ×20 dilutions). Dilutions must contain 0.1% KCl. 
     A standard Ca atomic absorption solution (e.g. BDH 1000 ppm Ca) was diluted with distilled water and an accurate pipette to give standards of 0.5, 4.0 and 10.0 ppm. 0.1% KCl is added to prevent ionic interference. To convert readings obtained from Ca to CaO a factor of 1.4 was used. 
     Magnesium may require dilutions on the sample before determinations can be made (i.e. ×10 and ×20). Add 0.1% KCl to each dilution. To convert Mg to MgO multiply by 1.658. 
     A standard Mg atomic absorption solution (e.g. BDH 1000 ppm Mg) was diluted with distilled water and an accurate pipette to give standards of 0.5, 1.0 and 10.0 ppm Mg. 0.1% KCl was added to prevent ionic interference. 
     All stock solutions were stored in plastic bottles 
     The results of the tests are indicated in Table 2. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 BODY FLUIDS SOLUBILITY 
               
               
                 (ppm) 
               
             
          
           
               
                   
                 SiO 2   
                   
                 CaO 
                   
                 MgO 
                   
               
             
          
           
               
                   
                 5 h 
                 24 h 
                 5 h 
                 24 h 
                 5 h 
                 24 h 
               
               
                   
                   
               
             
          
           
               
                   
                 SW-A 
                 98 
                 120 
                 63 
                 56 
                 33 
                 66 
               
               
                   
                 SW-A1 
                 83 
                 141 
                 32 
                 70 
                 21 
                 70 
               
               
                   
                 SW-A2 
                 130 
                 202 
                 43 
                 73 
                 100 
                 177 
               
               
                   
                 SW-B1 
                 58 
                 77 
                 10 
                 38 
                 5 
                 9 
               
               
                   
                 SW-B2 
                 64 
                 121 
                 27 
                 55 
                 5 
                 10 
               
               
                   
                 SW-B3 
                 138 
                 192 
                 80 
                 46 
                 8 
                 21 
               
               
                   
                   
               
             
          
         
       
     
     Fibres with the best solubility (SW-A2 and SW-B3) were then tested, after annealing at varying temperatures, and compared with the comparative examples of Table 1. The results are shown in Table 3. 
     It can be seen that for the SW-A2 fibre, with increasing annealing temperature, the silica solubility drops progressively. In contrast the SW-B3 composition shows no loss in solubility up to 800° C. and although a reduction in solubility is shown above that temperature it is not as dramatic as for SW-A2. Despite this difference in solubility it is to be noted that only the needled GF fibre shows a comparable silica solubility and that material melts at 700° C. 
     
       
         
               
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
             
             
               
                   
                   
               
               
                   
                 Solubility Analyses 
               
             
          
           
               
                   
                 CaO(ppm) 
                 MgO(ppm) 
                 SiO 2 (ppm) 
               
             
          
           
               
                 Fibre 
                 Condition 
                 5 hrs 
                 24 hrs 
                 5 hrs 
                 24 hrs 
                 5 hrs 
                 24 hrs 
               
               
                   
               
             
          
           
               
                 SW-A2 
                 As received 
                 58 
                 37 
                 37 
                 3 
                 89 
                 130 
               
               
                 SW-A2 
                  600° C., 48 hrs 
                 33 
                 56 
                 27 
                 43 
                 60 
                 108 
               
               
                 SW-A2 
                  800° C., 48 hrs 
                 35 
                 53 
                 17 
                 30 
                 43 
                 87 
               
               
                 SW-A2 
                 1000° C., 48 hrs 
                 7 
                 3 
                 3 
                 2 
                 11 
                 21 
               
               
                 SW-B3 
                 As received 
                 35 
                 69 
                 7 
                 22 
                 22 
                 100 
               
               
                 SW-B3 
                  600° C., 48 hrs 
                 61 
                 150 
                 12 
                 22 
                 55 
                 130 
               
               
                 SW-B3 
                  800° C., 48 hrs 
                 41 
                 90 
                 3 
                 7 
                 24 
                 144 
               
               
                 SW-B3 
                 1000° C., 48 hrs 
                 18 
                 40 
                 3 
                 3 
                 17 
                 60 
               
               
                 CRBT 
                 As received 
                 10 
                 8 
                 6 
                 3 
                 5 
                 3 
               
               
                 CHBT 
                 As received 
                 16 
                 10 
                 7 
                 3 
                 4 
                 0.3 
               
               
                 Glass Fibre 
                 As received 
                 14 
                 17 
                 5 
                 3 
                 5 
                 7 
               
               
                 Needled GF 
                 As received 
                 17 
                 34 
                 8 
                 15 
                 66 
                 85 
               
               
                 Needled GF 
                  600° C., 48 hrs 
                 11 
                 26 
                 7 
                 10 
                 19 
                 37 
               
               
                 Mineral Fibre 
                 As received 
                 16 
                 16 
                 7 
                 6 
                 8 
                 9 
               
               
                   
               
               
                 [The Glass Fibre and Needled Glass Fibre had the compositions shown in Table 1.] 
               
             
          
         
       
     
     The user is primarily concerned with the solubility of the fibre as received as it is in this condition that most handling occurs; as received both SW-A2 and SW-B3 fibres have extremely high solubility. Even after exposure to 800° C. and 1000° C. these fibres have solubilities much higher than other high temperature use fibres. 
     To investigate the reasons underlying the difference in solubilities after high temperature annealing between the SW-A2 and SW-B3 fibres qualitative X-ray diffraction was done on the fibres. The results are indicated in Table 4 and it can be seen that the SW-B3 fibre forms pseudowollastonite and wollastonite, whereas the SW-A2 fibre forms diopside. It appears therefore that the crystalline diopside has a lower solubility in physiological saline solution than the crystalline pseudowollastonite and wollastonite material precipitated from the SW-B3 fibre. 
     
       
         
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Sample 
                 Condition 
                 Qualitative XRD 
               
               
                   
               
             
             
               
                 SW-A2 
                  600° C., 48 hours 
                 Amorphous 
               
               
                 SW-A2 
                  800° C., 48 hours 
                 Amorphous with small amount Diopside 
               
               
                 SW-A2 
                 1000° C., 48 hours 
                 Diopside 
               
               
                 SW-B3 
                  600° C., 48 hours 
                 Amorphous 
               
               
                 SW-B3 
                  800° C., 48 hours 
                 Amorphous 
               
               
                 SW-B3 
                 1000° C., 48 hours 
                 Pseudowollastonite &amp; Wollastonite 
               
               
                   
               
             
          
         
       
     
     Various of the fibres were then tested for their shrinkage characteristics. Table 5 shows the results of Shrinkage tests on all the test fibres and on some of the comparative fibres. These results were obtained by proposed ISO standard ISO/TC33/SC2N220 (equivalent to British Standard BS 1920, part 6, 1986) with some modifications to account for small sample size. The method in summary comprises the manufacture of vacuum cast preforms, using 75 g of fibre in 500 cm 3  of 0.2% starch solution, into a 120×65 mm tool. Platinum pins (approx 0.1-0.3 mm diameter) were placed 100×45 mm apart in the 4 corners. The longest lengths (L1 &amp; L2) and the diagonals (L3 &amp; L4) were measured to an accuracy of .±0.01 mm using a travelling microscope attached to a steel rule with a vernier scale. The samples were placed in a furnace at temperature and left for 24 hours. The shrinkage values are given as an average of the 4 measurements. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 LINEAR SHRINKAGE (%) 
               
               
                 (24 h at temperature) 
               
             
          
           
               
                 Temp. ° C. 
                 SW-A 
                 SW-A1 
                 SW-A2 
                 SW-B1 
                 SW-B2 
                 SW-B3 
               
               
                   
               
             
          
           
               
                  730 
                 1.45 
                   
                 1.43 
                 1.02 
                 0.22 
                   
               
               
                  870 
                   
                   
                   
                 0.41 
               
               
                  900 
                   
                   
                 1.07 
                   
                   
                 1.07 
               
               
                 1000 
                   
                 1.04 
                 1.3 
                 0.51 
                 0.6 
                 1.1 
               
               
                 1100 
                   
                 0.71 
                 1.8 
                   
                 0.73 
                 2.2 
               
               
                 Maximum 
                 850 
                 1050 
                 1050 
                 1050 
                 1050 
                 1000 
               
               
                 Service 
               
               
                 Temperature 
               
               
                 ° C. 
               
               
                   
               
             
          
         
       
     
     It can be seen that in SW-A, SW-A1, SW-A2, SW-B1, SW-B2 and SW-B3, owing to the increase in molar volume on crystallisation, the linear shrinkage at the maximum service temperature is less than 3.5%. 
     Table 6 shows the results of a further series of shrinkage tests made in the same way. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 6 
               
               
                   
               
               
                   
                 Measurement 
                   
                   
                   
               
               
                   
                 Direction 
                 Test 
                 Linear 
               
               
                   
                 c.f. Roll 
                 Temperatures 
                 Shrinkages 
                 % 
               
               
                 Sample 
                 Direction 
                 ° C. 
                 Range 
                 Mean 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 SW-A2 
                 Parallel 
                 850 
                 1.1–1.4 
                 1.2 
               
               
                 SW-A2 
                 Perpendicular 
                 850 
                 0.7–1.5 
                 1.3 
               
               
                 SW-A2 
                 Parallel 
                 900 
                 0.5–1.1 
                 0.9 
               
               
                 SW-A2 
                 Perpendicular 
                 900 
                 1.9–4.5 
                 3.0 
               
               
                 SW-A2 
                 Parallel 
                 1000 
                 0.5–2.9 
                 1.3 
               
               
                 SW-A2 
                 Perpendicular 
                 1000 
                 1.7–2.9 
                 2.2 
               
               
                 SW-A2 
                 Parallel 
                 1100 
                 0.7–1.5 
                 1.0 
               
               
                 SW-A2 
                 Perpendicular 
                 1100 
                 1.0–2.6 
                 1.8 
               
               
                 SW-B3 
                 Parallel 
                 900 
                 1.6–1.8 
                 1.7 
               
               
                 SW-B3 
                 Perpendicular 
                 900 
                 1.4–2.4 
                 2.1 
               
               
                 SW-B3 
                 Parallel 
                 1000 
                 1.6–2.3 
                 1.9 
               
               
                 SW-B3 
                 Perpendicular 
                 1000 
                 1.0–2.3 
                 1.7 
               
             
          
           
               
                 SW-B3 
                 Parallel and 
                 1100 
                 Complete Melting 
               
               
                   
                 Perpendicular 
                   
                 (Lantern type remnant) 
               
               
                   
               
             
          
         
       
     
     To ascertain the applicability of these tests to long term usage a series of cyclic shrinkage tests were undertaken on the materials and the heating schedule used for these cyclic tests is shown in  FIG. 3 . 
     The results of the tests are shown in Tables 7 &amp; 8 (the two figures given for SW-B3 are due to slight differences in chemical analysis [the fibre at the end of a production run of fibre tends to have slightly differing composition to that at the beginning of a production run of fibre]). 
     As a further comparison with the above discussed materials a melt was made comprising 55% SiO 2 , 29.9% CaO and 18.6% MgO. Fibres made using this composition had a maximum service temperature of 700° C. and melted at 800° C. 
     As these results were encouraging the applicants conducted a further and extensive series of tests, concentrating on the SW-A2 and SW-B3 compositions, to ascertain the reproducibility of these results and the boundaries of the useful compositions. 
     Table 9 (three pages) below gives the compositions of a series of melts, ranked on silica content, and showing the shrinkage figure after exposure to 1000° C. for 24 hours (1st column) and 800° C. for 24 hours (2nd column). These shrinkages were measured by the same method as the shrinkages given above but measurements were made with a travelling microscope with a digital linear scale accurate to ±5 μm. It can clearly be seen that all fibres with a silica content of less than 58% have a shrinkage at 1000° C. of greater than 3.5% save two (B3-3 and 708). These fibres, together with some fibres with a silica content of greater than 58% although showing a reasonable figure at 1000° C., show a very poor figure at 800° C. Compositions with an SiO 2  content of greater than 70% appear to fiberise poorly. This may be because such compositions have two liquids in the melt as may be appreciated from  FIG. 1 . 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 7 
               
               
                   
               
               
                 CYCLIC SHRINKAGE (LINEAR) 
               
               
                 (%) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Product 
                 1000° C. 
                 1100° C. 
                 24 h at 
               
               
                   
                   
                   
                   
                 1000° C. 
               
               
                   
                 No. cycles 
                 58 
                 42 
               
               
                   
                 CRBT 
                 2.0 
                 2.7 
                 1.9 
               
               
                   
                 CWBT 
                 15.0 
                 13.3 
                 12.1 
               
               
                   
                 SW-A2 
                 0.33 
                 2.0 
                 1.3 
               
               
                   
                 SW-B3 
                 1.00 
                 1.67 
                 1.1 
               
               
                   
                 SW-B3 
                 0.33 
                 0.67 
                 1.1 
               
               
                   
                   
               
               
                   
                 Accuracy: + or − 0.33% 
               
             
          
         
       
     
     
       
         
               
             
               
               
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 CYCLIC SHRINKAGE 
               
               
                 (%) 
               
             
          
           
               
                   
                 LINEAR 
                   
               
               
                   
                 SHRINKAGE 
                 THICKNESS 
               
             
          
           
               
                   
                 24 h at 
                 SHRINKAGE 
               
             
          
           
               
                 PRODUCT 
                 1000° C. 
                 1100° C. 
                 1000° C. 
                 1000° C. 
                 1100° C. 
               
               
                   
               
             
          
           
               
                 No. cycles 
                 104 
                 100 
                   
                 104 
                 100 
               
               
                 CRBT 
                 1.47 
                 3.1 
                 1.9 
                 0.47 
                 11.19 
               
               
                 CWBT 
                 14.4 
                 15.2 
                 12.1 
                 38.63 
                 32.14 
               
               
                 SW-A2 
                 1.5 
                 2.1 
                 1.3 
                 8.58 
                 8.75 
               
               
                 SW-B3 
                 1.73 
                 1.63 
                 1.1 
                 7.24 
                 7.57 
               
               
                 SW-B3 
                 1.47 
                 1.77 
                 1.1 
                 7.02 
                 7.16 
               
               
                   
               
               
                 Accuracy: + or −0.3%(%) 
               
             
          
         
       
     
     
       
         
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 9 
               
             
             
               
                   
                   
               
               
                   
                 Analysed Compositions 
                 Shrinkage 
                 Rationalised 
               
               
                   
                 (Weight %) 
                 at ° C. 
                 Compositions 
               
             
          
           
               
                 Melt 
                 SiO 2  % 
                 CaO % 
                 MgO % 
                 Al 2 O 3  % 
                 Na 2 O % 
                 K 2 O % 
                 Fe 2 O 3  % 
                 ZrO 2  % 
                 1000 
                 800 
                 SiO 2  % 
                 CaO % 
                 MgO % 
               
               
                   
               
             
          
           
               
                 A2-28 
                 78.07 
                 2.07 
                 17.15 
                 0.15 
                 &lt;0.05 
                 &lt;0.05 
                 0.11 
                 1.76 
                 ¶ 
                   
                 80.3 
                 2.1 
                 17.6 
               
               
                 A2-16 
                 73.43 
                 12.40 
                 10.09 
                 0.19 
                 &lt;0.05 
                 &lt;0.05 
                 0.11 
                 2.23 
                 0.7 
                 * 
                 76.6 
                 12.9 
                 10.5 
               
               
                 A2-32 
                 73.09 
                 6.36 
                 19.60 
                 0.23 
                 0.05 
                 &lt;0.05 
                 0.11 
                 0.36 
                 ¶ 
                   
                 73.8 
                 6.4 
                 19.8 
               
               
                 B3-32 
                 72.38 
                 23.43 
                 0.65 
                 0.31 
                 0.31 
                 0.09 
                 0.22 
                 0.72 
                 ¶ 
                   
                 75.0 
                 24.3 
                 0.7 
               
               
                 A2-15 
                 72.25 
                 12.67 
                 12.35 
                 0.11 
                 &lt;0.05 
                 &lt;0.05 
                 0.10 
                 1.24 
                 1.1 
                 * 
                 74.3 
                 13.0 
                 12.7 
               
               
                 A2-22 
                 71.48 
                 9.36 
                 16.34 
                 0.33 
                 0.10 
                 &lt;0.05 
                 0.20 
                 0.83 
                 1.1 
                 * 
                 73.6 
                 9.6 
                 16.8 
               
               
                 A2-29 
                 71.24 
                 4.46 
                 22.31 
                 0.19 
                 &lt;0.05 
                 &lt;0.05 
                 0.13 
                 1.23 
                 1.8 
                 *1.5 
                 72.7 
                 4.5 
                 22.8 
               
               
                 A2-27 
                 71.14 
                 6.77 
                 19.64 
                 0.24 
                 0.08 
                 &lt;0.05 
                 0.13 
                 1.01 
                 1.2 
                 *1.2 
                 72.9 
                 7.0 
                 20.3 
               
               
                 B3-28 
                 70.81 
                 18.74 
                 7.03 
                 0.47 
                 0.23 
                 0.07 
                 0.16 
                 0.75 
                 0.2 
                 * 
                 73.3 
                 19.4 
                 7.3 
               
               
                 A2-17 
                 70.43 
                 11.58 
                 14.52 
                 0.15 
                 &lt;0.05 
                 &lt;0.05 
                 0.13 
                 1.58 
                 1.3 
                 * 
                 73.0 
                 12.0 
                 15.0 
               
               
                 A2-33 
                 70.04 
                 4.61 
                 22.85 
                 0.25 
                 0.11 
                 &lt;0.05 
                 0.12 
                 1.01 
                 ¶ 
                   
                 71.9 
                 4.7 
                 23.4 
               
               
                 B3-18 
                 69.42 
                 23.27 
                 3.76 
                 0.43 
                 0.37 
                 0.06 
                 0.12 
                 0.47 
                 0.4 
                   
                 72.0 
                 24.1 
                 3.9 
               
               
                 A2-6 
                 69.29 
                 15.17 
                 12.76 
                 0.07 
                 0.25 
                 &lt;0.05 
                 0.11 
                 1.13 
                 1.5 
                   
                 71.3 
                 15.6 
                 13.3 
               
               
                 B3-16 
                 68.74 
                 24.99 
                 1.71 
                 0.65 
                 0.38 
                 0.10 
                 0.24 
                 1.03 
                 0.3 
                 0.2 
                 72.0 
                 26.2 
                 1.8 
               
               
                 A2-26 
                 68.65 
                 8.12 
                 19.26 
                 0.29 
                 &lt;0.05 
                 &lt;0.05 
                 0.21 
                 0.98 
                 1.5 
                 1.5 
                 71.5 
                 8.4 
                 20.1 
               
               
                 B3-27 
                 68.56 
                 20.98 
                 7.00 
                 0.78 
                 0.35 
                 0.08 
                 0.17 
                 0.79 
                 0.8 
                 0.7 
                 71.0 
                 21.7 
                 7.3 
               
               
                 759 
                 68.33 
                 17.45 
                 12.60 
                 &lt;0.05 
                 0.11 
                 &lt;0.05 
                 0.33 
                 &lt;0.05 
                 1.7 
                 1.1 
                 69.5 
                 17.7 
                 12.8 
               
               
                 A2-20 
                 68.19 
                 11.58 
                 16.57 
                 0.40 
                 0.19 
                 0.05 
                 0.21 
                 0.91 
                 1.1 
                 1.0 
                 70.8 
                 12.0 
                 17.2 
               
               
                 A2-31 
                 67.62 
                 8.45 
                 21.72 
                 0.32 
                 0.09 
                 &lt;0.05 
                 0.15 
                 0.64 
                 2.3 
                 1.9 
                 69.2 
                 8.6 
                 22.2 
               
               
                 B3-31 
                 67.59 
                 27.76 
                 0.49 
                 0.40 
                 0.40 
                 0.11 
                 0.22 
                 1.01 
                 0.7 
                   
                 70.5 
                 29.0 
                 0.5 
               
               
                 B3-19 
                 67.58 
                 24.91 
                 3.65 
                 0.45 
                 0.37 
                 0.07 
                 0.15 
                 0.65 
                 0.5 
                   
                 70.3 
                 25.9 
                 3.8 
               
               
                 B3-17 
                 67.25 
                 26.68 
                 1.86 
                 0.70 
                 0.45 
                 0.10 
                 0.23 
                 0.57 
                 0.3 
                   
                 70.2 
                 27.9 
                 1.9 
               
               
                 A2-13 
                 66.67 
                 14.87 
                 16.01 
                 0.11 
                 0.05 
                 &lt;0.05 
                 0.10 
                 0.92 
                 1.6 
                   
                 68.4 
                 15.2 
                 16.4 
               
               
                 B3-22 
                 66.17 
                 21.28 
                 9.34 
                 0.52 
                 0.33 
                 0.08 
                 0.18 
                 0.54 
                 1.1 
                 0.8 
                 68.4 
                 22.0 
                 9.6 
               
               
                 A2-10 
                 66.17 
                 16.22 
                 15.80 
                 0.49 
                 0.06 
                 &lt;0.05 
                 0.09 
                 &lt;0.05 
                 2.2 
                 1.9 
                 67.4 
                 16.5 
                 16.1 
               
               
                 B3-15 
                 65.86 
                 29.82 
                 1.78 
                 0.47 
                 0.45 
                 0.08 
                 0.18 
                 0.51 
                 0.3 
                   
                 67.6 
                 30.6 
                 1.8 
               
               
                 719 
                 65.77 
                 25.69 
                 8.12 
                 &lt;0.05 
                 0.24 
                 &lt;0.05 
                 0.23 
                 &lt;0.05 
                 0.5 
                   
                 66.0 
                 25.8 
                 8.2 
               
               
                 A2-5 
                 65.69 
                 18.74 
                 13.78 
                 0.18 
                 0.16 
                 &lt;0.05 
                 0.10 
                 0.14 
                 1.9 
                 1.0 
                 66.9 
                 19.1 
                 14.0 
               
               
                 B3-4A 
                 65.50 
                 25.81 
                 4.88 
                 2.05 
                 0.28 
                 0.12 
                 0.16 
                 0.24 
                 1.4 
                 1.0 
               
               
                 A2-8 
                 65.33 
                 16.86 
                 14.24 
                 0.22 
                 0.13 
                 &lt;0.05 
                 0.14 
                 1.17 
                 1.5 
                   
                 67.7 
                 17.5 
                 14.8 
               
               
                 718 
                 65.23 
                 27.14 
                 6.95 
                 &lt;0.05 
                 0.24 
                 &lt;0.05 
                 0.20 
                 0.49 
                 0.4 
                   
                 65.7 
                 27.3 
                 7.0 
               
               
                 B3-14 
                 65.11 
                 24.91 
                 5.54 
                 0.58 
                 0.43 
                 0.09 
                 0.19 
                 0.61 
                 1.0 
                   
                 68.1 
                 26.1 
                 5.8 
               
               
                 721 
                 65.08 
                 27.26 
                 5.33 
                 0.06 
                 0.17 
                 &lt;0.05 
                 0.08 
                 &lt;0.05 
                 0.3 
                 0.6 
                 66.6 
                 27.9 
                 5.6 
               
               
                 A2-34 
                 64.85 
                 6.63 
                 26.20 
                 0.23 
                 0.06 
                 &lt;0.05 
                 0.16 
                 0.80 
                 3.4 
                 3.9 
                 66.4 
                 6.8 
                 26.8 
               
               
                 A2-21 
                 64.16 
                 13.74 
                 19.98 
                 0.34 
                 0.17 
                 &lt;0.05 
                 0.11 
                 0.13 
                 3.2 
                 3.3 
                 65.6 
                 14.0 
                 20.4 
               
               
                 B3-30 
                 64.13 
                 31.93 
                 0.37 
                 0.64 
                 0.45 
                 0.09 
                 0.14 
                 0.28 
                 0.6 
                   
                 66.5 
                 33.1 
                 0.4 
               
               
                 A2-35 
                 64.12 
                 8.88 
                 24.88 
                 0.29 
                 0.10 
                 &lt;0.05 
                 0.13 
                 0.47 
                 7.3 
                 7.1 
                 65.5 
                 9.1 
                 25.4 
               
               
                 B3-23 
                 64.09 
                 23.26 
                 9.33 
                 0.56 
                 0.36 
                 0.09 
                 0.16 
                 0.30 
                 1.0 
                   
                 66.3 
                 24.0 
                 9.7 
               
               
                 B3-5A 
                 63.74 
                 25.41 
                 4.68 
                 3.97 
                 0.26 
                 0.12 
                 0.17 
                 0.58 
                 7.4 
                 4.3 
               
               
                 A2-30 
                 63.68 
                 16.06 
                 18.21 
                 0.40 
                 0.11 
                 0.07 
                 0.15 
                 &lt;0.05 
                 2.7 
                 1.6 
                 65.0 
                 16.4 
                 18.6 
               
               
                 A2-9 
                 63.66 
                 21.44 
                 12.96 
                 1.49 
                 0.32 
                 0.10 
                 0.11 
                 &lt;0.05 
                 1.9 
                 0.9 
                 64.9 
                 21.9 
                 13.2 
               
               
                 A2-12 
                 63.56 
                 16.55 
                 18.00 
                 0.33 
                 0.11 
                 &lt;0.05 
                 0.08 
                 0.05 
                 1.0 
                 2.3 
                 64.8 
                 16.9 
                 18.3 
               
               
                 B3-6A 
                 63.24 
                 24.83 
                 4.59 
                 5.70 
                 0.27 
                 0.11 
                 0.15 
                 0.15 
                 21.6 
                 18.8 
               
               
                 723 
                 62.61 
                 29.79 
                 5.44 
                 &lt;0.05 
                 0.17 
                 &lt;0.05 
                 0.13 
                 &lt;0.05 
                 0.4 
                 0.5 
                 64.0 
                 30.4 
                 5.6 
               
               
                 757 
                 62.60 
                 20.92 
                 15.22 
                 0.20 
                 &lt;0.05 
                 &lt;0.05 
                 0.16 
                 &lt;0.05 
                 1.3 
                 2.9 
                 63.4 
                 21.2 
                 15.4 
               
               
                 A2-25 
                 62.36 
                 10.99 
                 24.18 
                 0.33 
                 0.10 
                 0.05 
                 0.16 
                 0.07 
                 6.1 
                   
                 63.9 
                 11.3 
                 24.8 
               
               
                 B3-13 
                 62.33 
                 30.62 
                 2.06 
                 0.55 
                 0.65 
                 0.09 
                 0.17 
                 0.91 
                 0.8 
                 0.9 
                 65.6 
                 32.2 
                 2.2 
               
               
                 A2-7 
                 61.98 
                 23.37 
                 11.98 
                 0.44 
                 0.25 
                 &lt;0.05 
                 0.10 
                 0.23 
                 1.4 
                   
                 63.7 
                 24.0 
                 12.3 
               
               
                 725 
                 61.83 
                 28.13 
                 7.54 
                 0.10 
                 0.36 
                 &lt;0.05 
                 0.17 
                 &lt;0.05 
                 0.6 
                   
                 63.4 
                 28.9 
                 7.7 
               
               
                 B3-11 
                 61.71 
                 33.25 
                 2.33 
                 0.69 
                 0.52 
                 0.12 
                 0.25 
                 0.59 
                 0.9 
                   
                 63.4 
                 34.2 
                 2.4 
               
               
                 B3-24 
                 61.62 
                 25.53 
                 9.73 
                 0.58 
                 0.38 
                 0.10 
                 0.17 
                 &lt;0.05 
                 1.8 
                 1.2 
                 63.6 
                 26.4 
                 10.0 
               
               
                 A2-24 
                 61.38 
                 13.62 
                 22.74 
                 0.31 
                 0.16 
                 &lt;0.05 
                 0.14 
                 0.08 
                 3.3 
                 12.3 
                 62.8 
                 13.9 
                 23.3 
               
               
                 722 
                 61.33 
                 31.08 
                 5.25 
                 0.05 
                 0.20 
                 &lt;0.05 
                 0.16 
                 &lt;0.05 
                 1.3 
                   
                 62.8 
                 31.8 
                 5.4 
               
               
                 924 
                 61.32 
                 19.78 
                 14.54 
                 2.57 
                 &lt;0.05 
                 &lt;0.05 
                 0.09 
                 0.66 
                 0.3 
                 3.0 
                 64.1 
                 20.7 
                 15.2 
               
               
                 B3-2A 
                 60.83 
                 32.30 
                 0.48 
                 4.15 
                 0.35 
                 0.15 
                 0.19 
                 0.12 
                 7.5 
                 3.3 
               
               
                 A2-14 
                 60.74 
                 25.30 
                 11.66 
                 0.28 
                 0.18 
                 0.05 
                 0.13 
                 0.16 
                 1.8 
                   
                 62.2 
                 25.9 
                 11.9 
               
               
                 B3-1A 
                 60.32 
                 32.27 
                 3.99 
                 1.74 
                 0.32 
                 0.10 
                 0.15 
                 0.09 
                 2.5 
                 1.7 
               
               
                 A2-11 
                 60.32 
                 24.28 
                 13.24 
                 0.25 
                 0.18 
                 &lt;0.05 
                 0.09 
                 0.08 
                 1.8 
                 1.1 
                 61.7 
                 24.8 
                 13.5 
               
               
                 B3-9 
                 60.28 
                 34.49 
                 2.50 
                 0.76 
                 0.50 
                 0.13 
                 0.28 
                 0.49 
                 1.6 
                 1.7 
                 62.0 
                 35.4 
                 2.6 
               
               
                 A2-23 
                 60.20 
                 18.59 
                 18.78 
                 0.48 
                 0.19 
                 0.08 
                 0.15 
                 0.05 
                 18.9 
                 10.7 
                 61.7 
                 19.1 
                 19.2 
               
               
                 B3-1 
                 60.11 
                 32.56 
                 3.80 
                 0.79 
                 0.54 
                 0.12 
                 0.23 
                 0.82 
                 0.5 
                   
                 62.3 
                 33.8 
                 3.9 
               
               
                 932 
                 59.85 
                 21.60 
                 15.65 
                 1.50 
                 0.06 
                 &lt;0.05 
                 0.18 
                 0.11 
                 12.8 
                   
                 61.6 
                 22.3 
                 16.1 
               
               
                 692 
                 59.82 
                 34.34 
                 5.44 
                 0.13 
                 0.19 
                 &lt;0.05 
                 0.08 
                 0.17 
                 2.1 
                   
                 60.0 
                 34.5 
                 5.5 
               
               
                 B3-3A 
                 59.54 
                 31.64 
                 0.67 
                 5.91 
                 0.33 
                 0.15 
                 0.21 
                 0.41 
                 43.3 
                 15.3 
               
               
                 B3-25 
                 59.53 
                 28.15 
                 9.22 
                 0.48 
                 0.39 
                 0.08 
                 0.14 
                 &lt;0.05 
                 2.3 
                   
                 61.4 
                 29.1 
                 9.5 
               
               
                 B3-29 
                 59.40 
                 36.00 
                 0.68 
                 0.92 
                 0.43 
                 0.14 
                 0.23 
                 0.17 
                 0.9 
                   
                 61.8 
                 37.5 
                 0.7 
               
               
                 714 
                 59.05 
                 32.00 
                 8.27 
                 &lt;0.05 
                 0.27 
                 &lt;0.05 
                 0.40 
                 &lt;0.05 
                 0.7 
                 1.2 
                 59.5 
                 32.2 
                 8.3 
               
               
                 696 
                 58.81 
                 30.91 
                 6.15 
                 0.21 
                 0.18 
                 &lt;0.05 
                 0.08 
                 0.24 
                 0.3 
                 1.4 
                 61.3 
                 32.3 
                 6.4 
               
               
                 A2-19 
                 58.71 
                 18.48 
                 19.74 
                 0.54 
                 0.20 
                 0.07 
                 0.19 
                 &lt;0.05 
                 4.7 
                   
                 60.6 
                 19.0 
                 20.4 
               
               
                 586 
                 58.65 
                 35.03 
                 3.90 
                 0.13 
                 0.23 
                 &lt;0.05 
                 0.16 
                 &lt;0.05 
                 1.9 
                 1.6 
                 60.1 
                 35.9 
                 4.0 
               
               
                 694 
                 58.39 
                 33.10 
                 6.02 
                 0.27 
                 0.20 
                 &lt;0.05 
                 0.10 
                 0.17 
                 1.6 
                 1.9 
                 59.9 
                 33.9 
                 6.2 
               
               
                 765 
                 57.78 
                 3.90 
                 35.07 
                 2.12 
                 &lt;0.05 
                 &lt;0.05 
                 0.23 
                 &lt;0.05 
                 34.2 
                   
                 59.7 
                 4.0 
                 36.3 
               
               
                 660 
                 57.74 
                 34.65 
                 4.83 
                 1.15 
                 0.24 
                 &lt;0.05 
                 0.19 
                 &lt;0.05 
                 24.7 
                   
                 59.4 
                 35.6 
                 5.0 
               
               
                 B3-20 
                 57.57 
                 32.70 
                 6.07 
                 0.91 
                 0.57 
                 0.13 
                 0.22 
                 &lt;0.05 
                 30.9 
                   
                 59.8 
                 33.9 
                 6.3 
               
               
                 712 
                 57.54 
                 35.39 
                 4.61 
                 0.06 
                 0.23 
                 &lt;0.05 
                 0.12 
                 &lt;0.05 
                 4.4 
                 3.4 
                 59.0 
                 36.3 
                 4.7 
               
               
                 B3-21 
                 57.38 
                 36.62 
                 2.43 
                 0.73 
                 0.52 
                 0.11 
                 0.16 
                 0.08 
                 30.3 
                   
                 59.5 
                 38.0 
                 2.5 
               
               
                 B3-26 
                 56.98 
                 30.50 
                 9.44 
                 0.62 
                 0.44 
                 0.11 
                 &lt;0.05 
                 &lt;0.05 
                 39.8 
                 26.6 
                 58.8 
                 31.5 
                 9.7 
               
               
                 A2-18 
                 56.96 
                 26.29 
                 13.01 
                 0.66 
                 0.51 
                 0.10 
                 0.19 
                 &lt;0.05 
                 36.2 
                   
                 59.2 
                 27.3 
                 13.5 
               
               
                 971 
                 56.82 
                 23.92 
                 17.36 
                 0.74 
                 0.18 
                 &lt;0.05 
                 0.14 
                 0.05 
                 41.7 
                   
                 57.9 
                 24.4 
                 17.7 
               
               
                 734 
                 56.58 
                 23.62 
                 17.05 
                 1.00 
                 0.06 
                 &lt;0.05 
                 0.13 
                 0.05 
                 39.3 
                   
                 58.2 
                 24.3 
                 17.5 
               
               
                 973 
                 56.18 
                 24.45 
                 16.81 
                 0.50 
                 0.08 
                 &lt;0.05 
                 0.14 
                 0.05 
                 34.9 
                   
                 57.7 
                 25.1 
                 17.2 
               
               
                 B3-3 
                 55.99 
                 36.07 
                 4.44 
                 0.58 
                 0.45 
                 0.09 
                 0.38 
                 1.46 
                 0.3 
                 34.7 
                 58.0 
                 37.4 
                 4.6 
               
               
                 708 
                 55.22 
                 42.79 
                 0.77 
                 &lt;0.05 
                 0.31 
                 &lt;0.05 
                 0.12 
                 &lt;0.05 
                 1.1 
                 8.7 
                 55.9 
                 43.3 
                 0.8 
               
               
                 71 
                 54.68 
                 24.04 
                 19.66 
                 0.20 
                 0.17 
                 &lt;0.05 
                 0.23 
                 &lt;0.05 
                 51.7 
                   
                 55.6 
                 24.4 
                 20.0 
               
               
                   
               
               
                 *Poor fibres containing a lot of shot. All other constituents &lt;0.1%. 
               
               
                 ¶ Too poor to test for solubility or shrinkage 
               
             
          
         
       
     
     
       
         
               
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 10 
               
             
             
               
                   
                   
               
               
                   
                   
                   
                 Rationalised 
               
               
                   
                 Analysed Compositions 
                 Solubilities 
                 Compositions 
               
             
          
           
               
                   
                 (Weight %) 
                 ppm 
                   
                   
                 MgO 
               
             
          
           
               
                 Melt 
                 SiO 2  % 
                 CaO % 
                 MgO % 
                 Al 2 O 3  % 
                 Na 2 O % 
                 K 2 O % 
                 Fe 2 O 3  % 
                 ZrO 2  % 
                 SiO 2   
                 Cao 
                 MgO 
                 SiO 2  % 
                 CaO % 
                 % 
               
               
                   
               
             
          
           
               
                 A2-28 
                 78.07 
                 2.07 
                 17.15 
                 0.15 
                 &lt;0.05 
                 &lt;0.05 
                 0.11 
                 1.76 
                 ¶ 
                   
                   
                 80.3 
                 2.1 
                 17.6 
               
               
                 A2-16 
                 73.43 
                 12.40 
                 10.09 
                 0.19 
                 &lt;0.05 
                 &lt;0.05 
                 0.11 
                 2.23 
                 113 
                 45 
                 55 
                 76.6 
                 12.9 
                 10.5 
               
               
                 A2-32 
                 73.09 
                 6.36 
                 19.60 
                 0.23 
                 0.05 
                 &lt;0.05 
                 0.11 
                 0.36 
                 ¶ 
                   
                   
                 73.8 
                 6.4 
                 19.8 
               
               
                 B3-32 
                 72.38 
                 23.43 
                 0.65 
                 0.31 
                 0.31 
                 0.09 
                 0.22 
                 0.72 
                 ¶ 
                   
                   
                 75.0 
                 24.3 
                 0.7 
               
               
                 A2-15 
                 72.25 
                 12.67 
                 12.35 
                 0.11 
                 &lt;0.05 
                 &lt;0.05 
                 0.10 
                 1.24 
                 105 
                 35 
                 48 
                 74.3 
                 13.0 
                 12.7 
               
               
                 A2-22 
                 71.48 
                 9.36 
                 16.34 
                 0.33 
                 0.10 
                 &lt;0.05 
                 0.20 
                 0.83 
                 126 
                 36 
                 75 
                 73.6 
                 9.6 
                 16.8 
               
               
                 A2-29 
                 71.24 
                 4.46 
                 22.31 
                 0.19 
                 &lt;0.05 
                 &lt;0.05 
                 0.13 
                 1.23 
                 94 
                 21 
                 105 
                 72.7 
                 4.5 
                 22.8 
               
               
                 A2-27 
                 71.14 
                 6.77 
                 19.64 
                 0.24 
                 0.08 
                 &lt;0.05 
                 0.13 
                 1.01 
                 101 
                 24 
                 67 
                 72.9 
                 7.0 
                 20.1 
               
               
                 B3-28 
                 70.81 
                 18.74 
                 7.03 
                 0.47 
                 0.23 
                 0.07 
                 0.16 
                 0.75 
                 108 
                 49 
                 31 
                 73.3 
                 19.4 
                 7.3 
               
               
                 A2-17 
                 70.43 
                 11.58 
                 14.52 
                 0.15 
                 &lt;0.05 
                 &lt;0.05 
                 0.13 
                 1.58 
                 91 
                 35 
                 72 
                 73.0 
                 12.0 
                 15.0 
               
               
                 A2-33 
                 70.04 
                 4.61 
                 22.85 
                 0.25 
                 0.11 
                 &lt;0.05 
                 0.12 
                 1.01 
                 ¶ 
                   
                   
                 71.9 
                 4.7 
                 23.4 
               
               
                 B3-18 
                 69.42 
                 23.27 
                 3.76 
                 0.43 
                 0.37 
                 0.06 
                 0.12 
                 0.47 
                 145 
                 66 
                 17 
                 72.0 
                 24.1 
                 3.9 
               
               
                 A2-6 
                 69.29 
                 15.17 
                 12.76 
                 0.07 
                 0.25 
                 &lt;0.05 
                 0.11 
                 1.13 
                 152 
                 48 
                 70 
                 71.3 
                 15.6 
                 13.1 
               
               
                 B3-16 
                 68.74 
                 24.99 
                 1.71 
                 0.65 
                 0.38 
                 0.10 
                 0.24 
                 2.03 
                 132 
                 72 
                 10 
                 72.0 
                 26.2 
                 1.8 
               
               
                 A2-26 
                 68.65 
                 8.12 
                 19.26 
                 0.29 
                 &lt;0.05 
                 &lt;0.05 
                 0.21 
                 0.98 
                 183 
                 31 
                 97 
                 71.5 
                 8.4 
                 20.1 
               
               
                 B3-27 
                 68.56 
                 20.98 
                 7.00 
                 0.78 
                 0.35 
                 0.08 
                 0.17 
                 0.79 
                 122 
                 54 
                 20 
                 71.0 
                 21.7 
                 7.3 
               
               
                 759 
                 68.33 
                 17.45 
                 12.60 
                 &lt;0.05 
                 0.11 
                 &lt;0.05 
                 0.33 
                 &lt;0.05 
                 117 
                 38 
                 40 
                 69.5 
                 17.7 
                 12.8 
               
               
                 A2-20 
                 68.19 
                 11.58 
                 16.57 
                 0.40 
                 0.19 
                 0.05 
                 0.21 
                 0.91 
                 162 
                 31 
                 69 
                 70.8 
                 12.0 
                 17.2 
               
               
                 A2-31 
                 67.62 
                 8.45 
                 21.72 
                 0.32 
                 0.09 
                 &lt;0.05 
                 0.15 
                 0.64 
                 103 
                 26 
                 72 
                 69.2 
                 8.6 
                 22.2 
               
               
                 B3-31 
                 67.59 
                 27.76 
                 0.49 
                 0.40 
                 0.40 
                 0.11 
                 0.22 
                 1.01 
                 112 
                 50 
                 4 
                 70.5 
                 29.0 
                 0.5 
               
               
                 B3-19 
                 67.58 
                 24.91 
                 3.65 
                 0.45 
                 0.37 
                 0.07 
                 0.15 
                 0.65 
                 163 
                 44 
                 21 
                 70.3 
                 25.9 
                 3.8 
               
               
                 B3-17 
                 67.25 
                 26.68 
                 1.86 
                 0.70 
                 0.45 
                 0.10 
                 0.23 
                 0.57 
                 162 
                 49 
                 13 
                 70.2 
                 27.9 
                 1.9 
               
               
                 A2-13 
                 66.67 
                 14.87 
                 16.01 
                 0.11 
                 0.05 
                 &lt;0.05 
                 0.10 
                 0.92 
                 159 
                 47 
                 70 
                 68.4 
                 15.2 
                 16.4 
               
               
                 A2-10 
                 66.17 
                 16.22 
                 15.80 
                 0.49 
                 0.06 
                 &lt;0.05 
                 0.09 
                 &lt;0.05 
                 122 
                 42 
                 52 
                 67.4 
                 16.5 
                 16.1 
               
               
                 B3-22 
                 66.17 
                 21.28 
                 9.34 
                 0.52 
                 0.33 
                 0.08 
                 0.18 
                 0.54 
                 174 
                 62 
                 57 
                 68.4 
                 22.0 
                 9.6 
               
               
                 B3-15 
                 65.86 
                 29.82 
                 1.78 
                 0.47 
                 0.45 
                 0.08 
                 0.18 
                 0.51 
                 156 
                 38 
                 7 
                 67.6 
                 30.6 
                 1.8 
               
               
                 719 
                 65.77 
                 25.69 
                 8.12 
                 &lt;0.05 
                 0.24 
                 &lt;0.05 
                 0.23 
                 &lt;0.05 
                 115 
                 51 
                 24 
                 66.0 
                 25.8 
                 8.2 
               
               
                 A2-5 
                 65.69 
                 18.74 
                 13.78 
                 0.18 
                 0.16 
                 &lt;0.05 
                 0.10 
                 0.14 
                 150 
                 48 
                 60 
                 66.9 
                 19.1 
                 14.0 
               
               
                 B3-4A 
                 65.50 
                 25.81 
                 4.88 
                 2.05 
                 0.28 
                 0.12 
                 0.16 
                 0.24 
                 82 
                 52 
                 16 
               
               
                 A2-8 
                 65.33 
                 16.86 
                 14.24 
                 0.22 
                 0.13 
                 &lt;0.05 
                 0.14 
                 1.17 
                 181 
                 54 
                 84 
                 67.7 
                 17.5 
                 14.8 
               
               
                 718 
                 65.23 
                 27.14 
                 6.95 
                 &lt;0.05 
                 0.24 
                 &lt;0.05 
                 0.20 
                 0.49 
                 107 
                 47 
                 20 
                 65.7 
                 27.3 
                 7.0 
               
               
                 B3-14 
                 65.11 
                 24.91 
                 5.54 
                 0.58 
                 0.43 
                 0.09 
                 0.19 
                 0.61 
                 158 
                 67 
                 27 
                 68.1 
                 26.1 
                 5.8 
               
               
                 721 
                 65.08 
                 27.26 
                 5.33 
                 0.06 
                 0.17 
                 &lt;0.05 
                 0.08 
                 &lt;0.05 
                 158 
                 68 
                 20 
                 66.6 
                 27.9 
                 5.5 
               
               
                 A2-34 
                 64.85 
                 6.63 
                 26.20 
                 0.23 
                 0.06 
                 &lt;0.05 
                 0.16 
                 0.80 
                 39 
                 11 
                 119 
                 66.4 
                 6.8 
                 26.8 
               
               
                 A2-21 
                 64.16 
                 13.74 
                 19.98 
                 0.34 
                 0.17 
                 &lt;0.05 
                 0.11 
                 0.13 
                 160 
                 28 
                 56 
                 65.6 
                 14.0 
                 20.4 
               
               
                 B3-30 
                 64.13 
                 31.93 
                 0.37 
                 0.64 
                 0.45 
                 0.09 
                 0.14 
                 0.28 
                 163 
                 83 
                 3 
                 66.5 
                 33.1 
                 0.4 
               
               
                 A2-35 
                 64.12 
                 8.88 
                 24.88 
                 0.29 
                 0.10 
                 &lt;0.05 
                 0.13 
                 0.47 
                 61 
                 18 
                 106 
                 65.5 
                 9.1 
                 25.4 
               
               
                 B3-23 
                 64.09 
                 23.26 
                 9.33 
                 0.56 
                 0.36 
                 0.09 
                 0.16 
                 0.30 
                 101 
                 44 
                 31 
                 66.3 
                 24.0 
                 9.7 
               
               
                 B3-5A 
                 63.74 
                 25.41 
                 4.68 
                 3.97 
                 0.26 
                 0.12 
                 0.17 
                 0.58 
                 48 
                 43 
                 11 
               
               
                 A2-30 
                 63.68 
                 16.06 
                 18.21 
                 0.40 
                 0.11 
                 0.07 
                 0.15 
                 &lt;0.05 
                 102 
                 33 
                 52 
                 65.0 
                 16.4 
                 18.6 
               
               
                 A2-9 
                 63.66 
                 21.44 
                 12.96 
                 1.49 
                 0.32 
                 0.10 
                 0.11 
                 &lt;0.05 
                 195 
                 67 
                 66 
                 64.9 
                 21.9 
                 13.2 
               
               
                 A2-12 
                 63.56 
                 16.55 
                 18.00 
                 0.33 
                 0.11 
                 &lt;0.05 
                 0.08 
                 0.05 
                 160 
                 47 
                 66 
                 64.8 
                 16.9 
                 18.3 
               
               
                 B3-6A 
                 63.24 
                 24.83 
                 4.59 
                 5.70 
                 0.27 
                 0.11 
                 0.15 
                 0.15 
                 26 
                 7 
                 26 
               
               
                 723 
                 62.61 
                 29.79 
                 5.44 
                 &lt;0.05 
                 0.17 
                 &lt;0.05 
                 0.13 
                 &lt;0.05 
                 141 
                 62 
                 17 
                 64.0 
                 30.4 
                 5.6 
               
               
                 757 
                 62.60 
                 20.92 
                 15.22 
                 0.20 
                 &lt;0.05 
                 &lt;0.05 
                 0.16 
                 &lt;0.05 
                 187 
                 62 
                 73 
                 63.4 
                 21.2 
                 15.4 
               
               
                 A2-25 
                 62.36 
                 10.99 
                 24.18 
                 0.33 
                 0.10 
                 0.05 
                 0.16 
                 0.07 
                 160 
                 35 
                 105 
                 63.9 
                 11.3 
                 24.8 
               
               
                 B3-13 
                 62.33 
                 30.62 
                 2.06 
                 0.55 
                 0.65 
                 0.09 
                 0.17 
                 0.91 
                 151 
                 41 
                 7 
                 65.6 
                 32.2 
                 2.2 
               
               
                 A2-7 
                 61.98 
                 23.37 
                 11.98 
                 0.44 
                 0.25 
                 &lt;0.05 
                 0.10 
                 0.23 
                 178 
                 59 
                 63 
                 63.7 
                 24.0 
                 12.3 
               
               
                 725 
                 61.83 
                 28.13 
                 7.54 
                 0.10 
                 0.36 
                 &lt;0.05 
                 0.17 
                 &lt;0.05 
                 186 
                 76 
                 35 
                 63.4 
                 28.9 
                 7.7 
               
               
                 B3-11 
                 61.71 
                 33.25 
                 2.33 
                 0.69 
                 0.52 
                 0.12 
                 0.25 
                 0.59 
                 162 
                 28 
                 15 
                 63.4 
                 34.2 
                 2.4 
               
               
                 B3-24 
                 61.62 
                 25.53 
                 9.73 
                 0.58 
                 0.38 
                 0.10 
                 0.17 
                 &lt;0.05 
                 185 
                 37 
                 57 
                 63.6 
                 26.4 
                 10.0 
               
               
                 A2-24 
                 61.38 
                 13.62 
                 22.74 
                 0.31 
                 0.16 
                 &lt;0.05 
                 0.14 
                 0.08 
                 136 
                 27 
                 87 
                 62.8 
                 13.9 
                 23.3 
               
               
                 722 
                 61.33 
                 31.08 
                 5.25 
                 0.05 
                 0.20 
                 &lt;0.05 
                 0.16 
                 &lt;0.05 
                 185 
                 81 
                 23 
                 62.8 
                 31.8 
                 5.4 
               
               
                 924 
                 61.32 
                 19.78 
                 14.54 
                 2.57 
                 &lt;0.05 
                 &lt;0.05 
                 0.09 
                 0.66 
                 77 
                 36 
                 37 
                 64.1 
                 20.7 
                 15.2 
               
               
                 B3-2A 
                 60.83 
                 32.30 
                 0.48 
                 4.15 
                 0.35 
                 0.15 
                 0.19 
                 0.12 
                 58 
                 61 
                 5 
               
               
                 A2-14 
                 60.74 
                 25.30 
                 11.66 
                 0.28 
                 0.18 
                 0.05 
                 0.13 
                 0.16 
                 127 
                 57 
                 43 
                 62.2 
                 25.9 
                 11.9 
               
               
                 B3-1A 
                 60.32 
                 32.27 
                 3.99 
                 1.74 
                 0.32 
                 0.10 
                 0.15 
                 0.09 
                 119 
                 72 
                 16 
               
               
                 A2-11 
                 60.32 
                 24.28 
                 13.24 
                 0.25 
                 0.18 
                 &lt;0.05 
                 0.09 
                 0.08 
                 149 
                 54 
                 51 
                 61.7 
                 24.8 
                 13.5 
               
               
                 B3-9 
                 60.28 
                 34.49 
                 2.50 
                 0.76 
                 0.50 
                 0.13 
                 0.28 
                 0.49 
                 175 
                 8 
                 5 
                 62.0 
                 35.4 
                 2.6 
               
               
                 A2-23 
                 60.20 
                 18.59 
                 18.78 
                 0.48 
                 0.19 
                 0.08 
                 0.15 
                 0.05 
                 192 
                 35 
                 47 
                 61.7 
                 19.1 
                 19.2 
               
               
                 B3-1 
                 60.11 
                 32.56 
                 3.80 
                 0.79 
                 0.54 
                 0.12 
                 0.23 
                 0.82 
                 146 
                 84 
                 17 
                 62.3 
                 33.8 
                 3.9 
               
               
                 932 
                 59.85 
                 21.60 
                 15.65 
                 1.50 
                 0.06 
                 &lt;0.05 
                 0.18 
                 0.11 
                 92 
                 41 
                 43 
                 61.6 
                 22.3 
                 16.1 
               
               
                 692 
                 59.82 
                 34.34 
                 5.44 
                 0.13 
                 0.19 
                 &lt;0.05 
                 0.08 
                 0.17 
                 140 
                 67 
                 23 
                 60.0 
                 34.5 
                 5.5 
               
               
                 B3-3A 
                 59.54 
                 31.64 
                 0.67 
                 5.91 
                 0.33 
                 0.15 
                 0.21 
                 0.41 
                 30 
                 25 
                 10 
               
               
                 B3-25 
                 59.53 
                 28.15 
                 9.22 
                 0.48 
                 0.39 
                 0.08 
                 0.14 
                 &lt;0.05 
                 133 
                 48 
                 33 
                 61.4 
                 29.1 
                 9.5 
               
               
                 B3-29 
                 59.40 
                 36.00 
                 0.68 
                 0.92 
                 0.43 
                 0.14 
                 0.23 
                 0.17 
                 201 
                 29 
                 5 
                 61.8 
                 37.5 
                 0.7 
               
               
                 714 
                 59.05 
                 32.00 
                 8.27 
                 &lt;0.05 
                 0.27 
                 &lt;0.05 
                 0.40 
                 &lt;0.05 
                 142 
                 73 
                 30 
                 59.5 
                 32.2 
                 8.3 
               
               
                 696 
                 58.81 
                 30.91 
                 6.15 
                 0.21 
                 0.18 
                 &lt;0.05 
                 0.08 
                 0.24 
                 163 
                 48 
                 37 
                 61.3 
                 32.3 
                 6.4 
               
               
                 A2-19 
                 58.71 
                 18.48 
                 19.74 
                 0.54 
                 0.20 
                 0.07 
                 0.19 
                 &lt;0.05 
                 125 
                 42 
                 66 
                 60.6 
                 19.0 
                 20.4 
               
               
                 586 
                 58.65 
                 35.03 
                 3.90 
                 0.13 
                 0.23 
                 &lt;0.05 
                 0.16 
                 &lt;0.05 
                 182 
                 54 
                 19 
                 60.1 
                 35.9 
                 4.0 
               
               
                 694 
                 58.39 
                 33.10 
                 6.02 
                 0.27 
                 0.20 
                 &lt;0.05 
                 0.10 
                 0.17 
                 133 
                 66 
                 27 
                 59.9 
                 33.9 
                 6.2 
               
               
                 765 
                 57.78 
                 3.90 
                 35.07 
                 2.12 
                 &lt;0.05 
                 &lt;0.05 
                 0.23 
                 &lt;0.05 
                 100 
                 16 
                 169 
                 59.7 
                 4.0 
                 36.3 
               
               
                 660 
                 57.74 
                 34.65 
                 4.83 
                 1.15 
                 0.24 
                 &lt;0.05 
                 0.19 
                 &lt;0.05 
                 152 
                 69 
                 23 
                 59.4 
                 35.6 
                 5.0 
               
               
                 B3-20 
                 57.57 
                 32.70 
                 6.07 
                 0.91 
                 0.57 
                 0.13 
                 0.22 
                 &lt;0.05 
                 181 
                 29 
                 40 
                 59.8 
                 33.9 
                 6.3 
               
               
                 712 
                 57.54 
                 35.39 
                 4.61 
                 0.06 
                 0.23 
                 &lt;0.05 
                 0.12 
                 &lt;0.05 
                 160 
                 24 
                 22 
                 59.0 
                 36.3 
                 4.7 
               
               
                 B3-21 
                 57.38 
                 36.62 
                 2.43 
                 0.73 
                 0.51 
                 0.11 
                 0.16 
                 0.08 
                 175 
                 25 
                 16 
                 59.5 
                 38.0 
                 2.5 
               
               
                 B3-26 
                 56.98 
                 30.50 
                 9.44 
                 0.62 
                 0.44 
                 0.11 
                 &lt;0.05 
                 &lt;0.05 
                 149 
                 64 
                 41 
                 58.8 
                 31.5 
                 9.7 
               
               
                 A2-18 
                 56.96 
                 26.29 
                 13.01 
                 0.66 
                 0.51 
                 0.10 
                 0.19 
                 &lt;0.05 
                 161 
                 47 
                 57 
                 59.2 
                 27.3 
                 13.5 
               
               
                 971 
                 56.82 
                 23.92 
                 17.36 
                 0.74 
                 0.18 
                 &lt;0.05 
                 0.14 
                 0.05 
                 142 
                 55 
                 73 
                 57.9 
                 24.4 
                 17.7 
               
               
                 734 
                 56.58 
                 23.62 
                 17.05 
                 1.00 
                 0.06 
                 &lt;0.05 
                 0.13 
                 0.05 
                 135 
                 52 
                 66 
                 58.2 
                 24.3 
                 17.5 
               
               
                 973 
                 56.18 
                 24.45 
                 16.81 
                 0.50 
                 0.08 
                 &lt;0.05 
                 0.14 
                 0.05 
                 102 
                 42 
                 47 
                 57.7 
                 25.1 
                 17.2 
               
               
                 B3-3 
                 55.99 
                 36.07 
                 4.44 
                 0.58 
                 0.45 
                 0.09 
                 0.38 
                 1.46 
                 185 
                 14 
                 18 
                 58.0 
                 37.4 
                 4.6 
               
               
                 708 
                 55.22 
                 42.79 
                 0.77 
                 &lt;0.05 
                 0.31 
                 &lt;0.05 
                 0.12 
                 &lt;0.05 
                 193 
                 31 
                 2 
                 55.9 
                 43.3 
                 0.8 
               
               
                 71 
                 54.68 
                 24.04 
                 19.66 
                 0.20 
                 0.17 
                 &lt;0.05 
                 0.23 
                 &lt;0.05 
                 133 
                 55 
                 62 
                 55.6 
                 24.4 
                 20.0 
               
               
                   
               
             
          
         
       
     
     There are several anomalies, namely compositions B3-6A, A 2 -25, A2-24, A2-23, B3-2A, B3-3A, A2-19, and 932. All of these have an SiO 2  content of &gt;58% but a high shrinkage. 
     On the assumption that the minimum silica level for satisfactory shrinkage varies with MgO content the applicants have determined that fibres with a silica content (in weight percent) that fail to meet the following expression do not have satisfactory shrinkages at either or both 800° C. and 1000° C.:— 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 SiO 2   
                 &gt;58% 
                 (for MgO =&lt; 10%) and 
               
               
                   
                 SiO 2   
                 &gt;58% + 0.5 (%MgO − 10) 
                 (for MgO &gt;= 10%) 
               
               
                   
                   
               
             
          
         
       
     
     The applicants have further found that the Al 2 O 3  content is important. From their studies it appears that the maximum Al 2 O 3  content lies somewhere between 2.57% and 3.97%. The applicants have found that with increasing alumina levels the first material to crystallise is calcium aluminate and this possibly forms a liquid phase that assists flow and hence shrinkage. 
     Table 10 shows, for the same compositions as Table 9, 24 hour solubilities for each major constituent. It can be seen that all of the compositions have high solubilities. 
     As mentioned above use of CaO in forming calcium containing fibres is inconvenient and can be hazardous. The applicants investigated use of mixed oxide materials that would avoid the handling of CaO. A fibre was made by admixture of magnesia with silica and wollastonite (CaSiO 3 ). 
     The raw materials used to make the melt comprised:— 
     Pennine Darlington Heavy Magnesia (#200) 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 MgO 
                 92.60% 
               
               
                   
                 CaO 
                 1.75% 
               
               
                   
                 Fe 2 O 3   
                 0.04% 
               
               
                   
                 SiO 2   
                 0.20% 
               
               
                   
                 Cl 
                 0.25% 
               
               
                   
                 SO 3   
                 0.70% 
               
               
                   
                 LOI 
                 4.50% 
               
               
                   
                   
               
             
          
         
       
     
     Partek&#39;s Finnish Low Iron Wollastonite (#200) 
     (U.K. agent—Cornelius Chemical Co., Romford, Essex) 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 SiO 2   
                 51.80% 
               
               
                   
                 CaO 
                 44.50% 
               
               
                   
                 MgO 
                 0.80% 
               
               
                   
                 Al 2 O 3   
                 0.60% 
               
               
                   
                 Fe 2 O 3   
                 0.30% 
               
               
                   
                 Na 2 O 
                 0.10% 
               
               
                   
                 K 2 O 
                 0.05% 
               
               
                   
                 TiO 2   
                 0.05% 
               
               
                   
                 S 
                 0.02% 
               
               
                   
                 MnO 
                 0.01% 
               
               
                   
                 P 
                 0.01% 
               
               
                   
                 F 
                 0.01% 
               
               
                   
                 LOI 
                 1.70% 
               
               
                   
                   
               
             
          
         
       
     
     Hepworth Mineral&#39;s Redhill T washed silica sand 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 SiO 2   
                 99.0% min. 
               
               
                   
                   
               
             
          
         
       
     
     These constituents were mixed as 78.65% Wollastonite; 19.25% SiO 2 ; and 3.6% MgO. This gave 0.4-0.5% of the final melt as Al 2 O 3.    
     It was surprisingly found that in producing a melt using these constituents the current requirements were only two-thirds that for the use of the raw oxides. 
     Fibre was produced by blowing (although spinning and other methods can be used). 2 runs were performed with different blowing conditions. 
     Chemical analysis was undertaken by the Analytical Department at the applicant&#39;s subsidiary Morgan Materials Technology (hereinafter called M 2 T) using wet chemical techniques. Fibre diameters were measured using M 2 T&#39;s Galai particle analyser, with shape analysis software. Typically 40,000 fibres were analysed for each run. 
     The first result of note was the speed of melt reaction when using wollastonite as compared with lime. Also the current was seen to be very stable throughout the growth of the melt. If the current was lost whilst pulling the electrodes apart the current could be restored simply by pushing them back together again. This was not possible with the runs using lime. 
                                                                                                         Chemical Analysis                Others   CaO   MgO   Al 2 O 3     SiO 2     ZrO 2     Na 2 O   Total                    Run 1   0.7   32.6   3.8   0.8   60.1   0.8   0.5   99.3       Run 2   0.7   32.5   3.8   0.8   60.1   0.8   0.6   99.3                    
Runs 1 and 2 indicate the respective x-ray fluorescence analyses for each run.
 
     
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
               
               
                 Shrinkage Results (1000° C. for 24 hours) 
               
             
          
           
               
                   
                   
                 L1 
                 L2 
                 L3 
                 L4 
                 Av. 
                 Std. Dev. 
               
               
                   
                   
               
             
          
           
               
                   
                 Run 1 
                 0.9 
                 0.2 
                 0.4 
                 0.6 
                 0.5 
                 0.3 
               
               
                   
                 Run 2(A) 
                 1.0 
                 −0.2 
                 0.7 
                 0.6 
                 0.5 
                 0.5 
               
               
                   
                 Run 2(b) 
                 0.5 
                 0.2 
                 0.0 
                 0.4 
                 0.2 
                 0.2 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 Solubility Results (ppm) 
               
             
          
           
               
                   
                 CaO 
                 MgO 
                 SiO 2   
               
               
                   
                   
               
             
          
           
               
                   
                 Run 1(5 hr) 
                 67 
                 10 
                  95 
               
               
                   
                 Run 1(24 hr) 
                 84 
                 17 
                 146 
               
               
                   
                 Run 2(5 hr) 
                 39 
                  7 
                  72 
               
               
                   
                 Run 2(24 hr) 
                 73 
                 17 
                 186 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Fibre diameters 
               
             
          
           
               
                   
                 Mean 
                 Median 
                 100%&lt; 
                 %&gt;5 μm 
                 %&lt;1 μm 
               
               
                   
                   
               
             
          
           
               
                 Run 1 
                 5.1 μm 
                 3.4 μm 
                 30 μm 
                 33% 
                 13% 
               
               
                 Run 2 
                 4.1 μm 
                 2.7 μm 
                 25 μm 
                 25% 
                 19% 
               
               
                   
               
             
          
         
       
     
     Accordingly it appears to be the case that by using what are cheaper ingredients than the pure oxides one can obtain a fibre that has as high a performance as using purer oxides and at much improved energy costs and safety. It is to be noted that this feature of the invention is not limited to saline soluble fibres and any oxide fibre that contains both calcium and silicon can advantageously be made with a calcium silicate, wollastonite being merely an example of such a silicate. 
     The previous description is directed towards high temperature usage of particular saline soluble fibres. The following is directed towards the prediction and use of saline soluble fibres. A series of fritted glass melts were made of the compositions shown in Tables 11A and 11B and quenched in water. Solubilities of the various components of the quenched melt were measured by the previously described method of atomic absorption. The solubilities were normalised to a specific surface area of 0.25 m 2 /gram of fibre. 
     The free energy of hydration was calculated by normalising the chemical analysis to 100 weight %; making the assumption that simple silicates (MSiO 3 /M 2  SiO 3 ) are present and calculating the free energy of hydration contribution of each species; and summing to get the total free energy of hydration. The data in Tables 11A &amp; 11B is also presented in  FIG. 4 . It can be seen that the fibres lie on a generally straight line bar four groups of materials that will be explained below. 
     Table 11 shows in each column the following:—
         Fibre reference   Composition   Molar ratios   Moles/100 grams of melt   Species assumed (see below)   Calculated free energy of hydration of assumed species (kcal/100 grams)(see below)   Calculated free energy of hydration of assumed species (kJ/kg) (see below)   Solubility data (# indicates not measured [see below])   Specific surface area   Normalised solubility data   log normalised solubility       

     The base data on which calculation of the free energy of hydration was done is set out in Tables 12 which indicates free energies of hydration taken from the literature in the units kcal/mol and kJ/mol. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Table of Free Energy of Hydration Values for Silicate Melts 
               
             
          
           
               
                   
                   
                   
                   
                   
                   
                 Free 
                   
                   
                   
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                 Energy 
                 Free 
               
               
                   
                   
                   
                   
                   
                   
                 of 
                 Energy 
                   
                   
                 Normal- 
               
               
                   
                 Composition 
                   
                 Moles 
                   
                   
                 Hydration 
                 of 
                   
                   
                 ized 
                 Log 
               
             
          
           
               
                 Melt 
                   
                 Wt. 
                 Ration- 
                   
                 in 
                   
                 Moles 
                 (kcal/ 
                 Hydration 
                 Solubility 
                 S.S.A 
                 Solu- 
                 (norm 
               
             
          
           
               
                 Code 
                 Oxide 
                 % 
                 alized 
                 Moles 
                 100 g 
                 Species 
                 in 1 kg 
                 100 g) 
                 (kj/kg) 
                 Oxide 
                 (ppm) 
                 m2/g 
                 bility 
                 solub) 
               
               
                   
               
             
          
           
               
                 CAS10(B) - 
                 CaO 
                 47.2 
                 47.8 
                 0.852 
                 0.451 
                 CaSiO3 
                 4.51 
                 −7.3 
                 −304.0 
                 CaO 
                 44 
                 0.30 
                 43 
                 1.63 
               
               
                 A 
                 Al2O3 
                 24.5 
                 24.8 
                 0.243 
                 0.243 
                 Al2O3 
                 2.43 
                 0.8 
                 31.6 
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 27.1 
                 27.4 
                 0.451 
                 0.401 
                 CaO 
                 4.01 
                 −5.3 
                 −219.7 
                 SiO2 
                 7 
               
               
                   
                 Total 
                 98.8 
                 100.0 
                   
                   
                   
                   
                 −11.8 
                 −492.1 
                 Total 
                 51 
               
               
                 CAS10(B) - 
                 CaO 
                 46.5 
                 47.2 
                 0.842 
                 0.479 
                 CaSiO3 
                 4.79 
                 −7.7 
                 −322.8 
                 CaO 
                 58 
                 0.39 
                 66 
                 1.82 
               
               
                 B 
                 Al2O3 
                 23.7 
                 24.0 
                 0.235 
                 0.235 
                 Al2O3 
                 2.35 
                 0.7 
                 30.6 
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 28.4 
                 28.8 
                 0.479 
                 0.363 
                 CaO 
                 3.63 
                 −4.8 
                 −198.9 
                 SiO2 
                 44 
               
               
                   
                 Total 
                 98.6 
                 100.0 
                   
                   
                   
                   
                 −11.8 
                 −491.1 
                 Total 
                 103 
               
               
                 CAS10(B) - 
                 CaO 
                 47.8 
                 48.4 
                 0.863 
                 0.456 
                 CaSiO3 
                 4.56 
                 −7.3 
                 −307.3 
                 CaO 
                 55 
                 0.36 
                 76 
                 1.88 
               
               
                 C 
                 Al2O3 
                 23.9 
                 24.2 
                 0.237 
                 0.237 
                 Al2O3 
                 2.37 
                 0.7 
                 30.8 
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 27.1 
                 27.4 
                 0.456 
                 0.407 
                 CaO 
                 4.07 
                 −5.3 
                 −223.0 
                 SiO2 
                 55 
               
               
                   
                 Total 
                 98.8 
                 100.0 
                   
                   
                   
                   
                 −11.9 
                 −499.5 
                 Total 
                 110 
               
               
                 CIS(A) 
                 CaO 
                 42.7 
                 44.3 
                 0.790 
                 0.707 
                 CaSiO3 
                 7.07 
                 −11.4 
                 −476.5 
                 CaO 
                 62 
                 0.40 
                 69 
                 1.84 
               
               
                   
                 TiO2 
                 12.7 
                 13.2 
                 0.165 
                 0.083 
                 CaO 
                 0.83 
                 −1.1 
                 −45.5 
                 TiO2 
                 0 
               
               
                   
                 SiO2 
                 41.0 
                 42.5 
                 0.707 
                 0.165 
                 TiO2 
                 1.65 
                 2.6 
                 110.4 
                 SiO2 
                 49 
               
               
                   
                 Total 
                 96.4 
                 100.0 
                   
                   
                   
                   
                 −9.9 
                 −411.6 
                 Total 
                 111 
               
               
                 SrSiO3 
                 SrO 
                 63.1 
                 64.4 
                 0.622 
                 0.592 
                 SrSiO3 
                 5.92 
                 −14.4 
                 −604.4 
                 SrO 
                 2 
                 0.37 
                 249 
                 2.40 
               
               
                   
                 SiO2 
                 34.9 
                 35.6 
                 0.592 
                 0.030 
                 SiO 
                 0.30 
                 −0.5 
                 −21.7 
                 SrO2 
                 367 
               
               
                   
                 Total 
                 98.0 
                 100.0 
                   
                   
                   
                   
                 −14.9 
                 −626.1 
                 Total 
                 369 
               
               
                 CaSiO3 
                 CaO 
                 46.1 
                 46.9 
                 0.836 
                 0.836 
                 CaSiO3 
                 8.36 
                 −13.5 
                 −563.5 
                 CaO 
                 41 
                 0.45 
                 163 
                 2.21 
               
               
                   
                 SiO2 
                 52.3 
                 53.1 
                 0.884 
                 0.048 
                 SiO2 
                 0.48 
                 0.3 
                 11.2 
                 SiO2 
                 253 
               
               
                   
                 Total 
                 98.4 
                 100.0 
                   
                   
                   
                   
                 −13.2 
                 −552.3 
                 Total 
                 294 
               
               
                 MAS(A) 
                 Na2O 
                 18.8 
                 18.9 
                 0.305 
                 0.305 
                 Na2SiO3 
                 3.05 
                 −8.8 
                 −367.5 
                 Na2O 
                 # 
                 0.56 
                 4 
                 0.60 
               
               
                   
                 Al2O3 
                 39.7 
                 39.8 
                 0.390 
                 0.390 
                 Al2O3 
                 3.90 
                 1.2 
                 50.7 
                 Al2O3 
                 4 
               
               
                   
                 SiO2 
                 41.1 
                 41.3 
                 0.687 
                 0.382 
                 SiO2 
                 3.82 
                 2.1 
                 89.4 
                 SiO2 
                 5 
               
               
                   
                 Total 
                 99.6 
                 100.0 
                   
                   
                   
                   
                 −5.5 
                 −227.4 
                 Total 
                 9 
               
               
                 CAS4 
                 CaO 
                 21.0 
                 20.9 
                 0.373 
                 0.373 
                 CaSiO3 
                 3.73 
                 −6.0 
                 −251.4 
                 CaO 
                 11 
                 0.62 
                 8 
                 0.90 
               
               
                   
                 Al2O3 
                 35.4 
                 35.2 
                 0.345 
                 0.345 
                 Al2O3 
                 3.45 
                 1.1 
                 44.9 
                 Al2O3 
                 4 
               
               
                   
                 SiO2 
                 44.2 
                 43.9 
                 0.731 
                 0.358 
                 SiO2 
                 7.31 
                 2.0 
                 171.1 
                 SiO2 
                 5 
               
               
                   
                 Total 
                 100.6 
                 100.0 
                   
                   
                   
                   
                 −2.9 
                 −35.4 
                 Total 
                 20 
               
               
                 MAS(B) 
                 MgO 
                 10.0 
                 10.3 
                 0.256 
                 0.256 
                 MgSiO3 
                 2.56 
                 −3.6 
                 −149.0 
                 MgO 
                 7 
                 0.52 
                 6 
                 0.78 
               
               
                   
                 Al2O3 
                 33.7 
                 34.9 
                 0.342 
                 0.342 
                 Al2O3 
                 3.42 
                 1.1 
                 44.5 
                 Al2O3 
                 2 
               
               
                   
                 SiO2 
                 53.0 
                 54.8 
                 0.912 
                 0.656 
                 SiO2 
                 6.56 
                 3.7 
                 153.5 
                 SiO2 
                 4 
               
               
                   
                 Total 
                 96.7 
                 100.0 
                   
                   
                   
                   
                 1.2 
                 49.0 
                 Total 
                 13 
               
               
                 SAS(A) 
                 SrO 
                 29.8 
                 30.5 
                 0.294 
                 0.294 
                 SrSiO3 
                 2.94 
                 −7.2 
                 −300.2 
                 SrO 
                 9 
                 0.50 
                 8 
                 0.90 
               
               
                   
                 Al2O3 
                 31.1 
                 31.8 
                 0.312 
                 0.312 
                 Al2O3 
                 3.12 
                 1.0 
                 40.6 
                 Al2O3 
                 2 
               
               
                   
                 SiO2 
                 36.8 
                 37.7 
                 0.627 
                 0.333 
                 SiO2 
                 3.33 
                 1.9 
                 77.9 
                 SiO2 
                 5 
               
               
                   
                 Total 
                 97.7 
                 100.0 
                   
                   
                   
                   
                 −4.3 
                 −181.7 
                 Total 
                 16 
               
               
                 SCS(A) 
                 SrO 
                 35.0 
                 35.1 
                 0.339 
                 0.339 
                 SrSiO3 
                 3.39 
                 −8.3 
                 −346.1 
                 SrO 
                 75 
                 0.41 
                 280 
                 2.45 
               
               
                   
                 CaO 
                 21.0 
                 21.1 
                 0.376 
                 0.376 
                 CaSiO3 
                 3.76 
                 −6.1 
                 −253.4 
                 CaO 
                 30 
               
               
                   
                 SiO2 
                 43.6 
                 43.8 
                 0.729 
                 0.014 
                 SiO2 
                 0.14 
                 0.1 
                 3.3 
                 SiO2 
                 355 
               
               
                   
                 Total 
                 99.6 
                 100.0 
                   
                   
                   
                   
                 −14.3 
                 −596.2 
                 Total 
                 460 
               
               
                 SMAS(A) 
                 SrO 
                 55.0 
                 56.6 
                 0.546 
                 0.296 
                 SrSiO3 
                 2.96 
                 −7.2 
                 −302.2 
                 SrO 
                 57 
                 0.46 
                 38 
                 1.58 
               
               
                   
                 MgO 
                 1.2 
                 1.2 
                 0.030 
                 0.030 
                 MgO 
                 0.30 
                 −0.2 
                 −8.2 
                 MgO 
                 2 
               
               
                   
                 Al2O3 
                 23.7 
                 24.4 
                 0.239 
                 0.239 
                 Al2O3 
                 2.39 
                 0.7 
                 31.1 
                 Al2O3 
                 5 
               
               
                   
                 SiO2 
                 17.3 
                 17.8 
                 0.296 
                 0.250 
                 SrO 
                 2.50 
                 −4.3 
                 −181.0 
                 SiO2 
                 5 
               
               
                   
                 Total 
                 97.2 
                 100.0 
                   
                   
                   
                   
                 −11.0 
                 −460.3 
                 Total 
                 69 
               
               
                 SMAS(B) 
                 SrO 
                 55.0 
                 55.9 
                 0.539 
                 0.401 
                 SrSiO3 
                 4.01 
                 −9.8 
                 −409.4 
                 SrO 
                 110 
                 0.39 
                 95 
                 1.98 
               
               
                   
                 MgO 
                 4.8 
                 4.9 
                 0.122 
                 0.122 
                 MgO 
                 1.22 
                 −0.8 
                 −33.2 
                 MgO 
                 15 
               
               
                   
                 Al2O3 
                 14.8 
                 15.1 
                 0.148 
                 0.148 
                 Al2O3 
                 1.48 
                 0.5 
                 19.2 
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 23.7 
                 24.1 
                 0.401 
                 0.138 
                 SrO 
                 1.38 
                 −2.4 
                 −99.9 
                 SiO2 
                 22 
               
               
                   
                 Total 
                 98.3 
                 100.0 
                   
                   
                   
                   
                 −12.5 
                 −523.3 
                 Total 
                 148 
               
               
                 SMS(A) 
                 SrO 
                 33.0 
                 32.9 
                 0.318 
                 0.318 
                 SrSiO3 
                 3.18 
                 −7.8 
                 −324.7 
                 SrO 
                 147 
                 0.39 
                 212 
                 2.33 
               
               
                   
                 MgO 
                 12.5 
                 12.5 
                 0.310 
                 0.310 
                 MgSiO3 
                 3.10 
                 −4.3 
                 −180.4 
                 MgO 
                 61 
               
               
                   
                 Al2O3 
                 1.0 
                 1.0 
                 0.010 
                 0.010 
                 Al2O3 
                 0.10 
                 0.0 
                 1.3 
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 53.8 
                 53.6 
                 0.892 
                 0.264 
                 SiO2 
                 2.64 
                 1.5 
                 61.8 
                 SiO2 
                 125 
               
               
                   
                 Total 
                 100.3 
                 100.0 
                   
                   
                   
                   
                 −10.6 
                 −442.0 
                 Total 
                 331 
               
               
                 SAS(C) 
                 SrO 
                 56.0 
                 56.2 
                 0.542 
                 0.401 
                 SrSiO3 
                 4.01 
                 −9.8 
                 −409.4 
                 SrO 
                 70 
                 0.38 
                 52 
                 1.72 
               
               
                   
                 Al2O3 
                 19.7 
                 19.7 
                 0.193 
                 0.193 
                 Al2O3 
                 1.93 
                 0.6 
                 25.1 
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 24.0 
                 24.1 
                 0.401 
                 0.141 
                 SrO 
                 1.41 
                 −2.4 
                 −102.1 
                 SiO2 
                 8 
               
               
                   
                 Total 
                 99.7 
                 100.0 
                   
                   
                   
                   
                 −11.6 
                 −486.4 
                 Total 
                 79 
               
               
                 CMAS(A) 
                 CaO 
                 35.0 
                 34.6 
                 0.617 
                 0.293 
                 CaSiO3 
                 2.93 
                 −4.7 
                 −197.5 
                 CaO 
                 11 
                 0.30 
                 24 
                 1.38 
               
               
                   
                 MgO 
                 4.5 
                 4.4 
                 0.109 
                 0.109 
                 MgO 
                 1.09 
                 −0.7 
                 −29.6 
                 MgO 
                 7 
               
               
                   
                 Al2O3 
                 44.0 
                 43.4 
                 0.426 
                 0.426 
                 Al2O3 
                 4.26 
                 1.3 
                 55.4 
                 Al2O3 
                 3 
               
               
                   
                 SiO2 
                 17.8 
                 17.6 
                 0.293 
                 0.324 
                 CaO 
                 3.24 
                 −4.2 
                 −177.6 
                 SiO2 
                 8 
               
               
                   
                 Total 
                 101.3 
                 100.0 
                   
                   
                   
                   
                 −8.3 
                 −349.3 
                 Total 
                 29 
               
               
                 SWA2 
                 CaO 
                 21.7 
                 21.7 
                 0.387 
                 0.387 
                 CaSiO3 
                 3.87 
                 −6.2 
                 −260.8 
                 CaO 
                 53 
                 0.48 
                 119 
                 2.08 
               
               
                   
                 MgO 
                 15.7 
                 15.7 
                 0.389 
                 0.389 
                 MgSiO3 
                 3.89 
                 −5.4 
                 −226.4 
                 MgO 
                 57 
               
               
                   
                 Al2O3 
                 0.8 
                 0.8 
                 0.008 
                 0.008 
                 Al2O3 
                 0.08 
                 0.0 
                 1.0 
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 61.8 
                 61.8 
                 1.028 
                 0.252 
                 SiO2 
                 2.52 
                 1.4 
                 59.0 
                 SiO2 
                 118 
               
               
                   
                 Total 
                 100.0 
                 100.0 
                   
                   
                   
                   
                 −10.2 
                 −427.2 
                 Total 
                 228 
               
               
                 SAS(D) 
                 SrO 
                 56.5 
                 57.3 
                 0.553 
                 0.413 
                 SrSiO3 
                 4.13 
                 −10.1 
                 −421.7 
                 SrO 
                 107 
                 0.40 
                 92 
                 1.96 
               
               
                   
                 Al2O3 
                 17.6 
                 17.9 
                 0.176 
                 0.176 
                 Al2O3 
                 1.76 
                 0.5 
                 22.9 
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 24.4 
                 24.8 
                 0.413 
                 0.140 
                 SrO 
                 1.40 
                 −2.4 
                 −101.4 
                 SiO2 
                 39 
               
               
                   
                 Total 
                 98.5 
                 100.0 
                   
                   
                   
                   
                 −12.0 
                 −500.2 
                 Total 
                 147 
               
               
                 KMAS(A) 
                 K2O 
                 16.5 
                 16.5 
                 0.175 
                 0.175 
                 K2SiO3 
                 1.75 
                 −7.3 
                 −305.4 
                 K2O 
                 # 
                 0.36 
                 14 
                 1.15 
               
               
                   
                 MgO 
                 13.0 
                 13.0 
                 0.323 
                 0.323 
                 MgSiO3 
                 3.23 
                 −2.1 
                 −188.0 
                 MgO 
                 8 
               
               
                   
                 Al2O3 
                 18.0 
                 17.9 
                 0.176 
                 0.176 
                 Al2O3 
                 1.76 
                 0.5 
                 22.9 
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 52.8 
                 52.6 
                 0.875 
                 0.377 
                 SiO2 
                 8.75 
                 2.1 
                 204.8 
                 SiO2 
                 11 
               
               
                   
                 Total 
                 100.3 
                 100.0 
                   
                   
                   
                   
                 −6.8 
                 −265.7 
                 Total 
                 20 
               
               
                   
               
             
          
         
       
     
     
       
         
               
               
             
               
               
               
             
               
               
               
             
           
               
                   
                 TABLE 12 
               
             
             
               
                   
                   
               
               
                   
                 G hyd   
               
             
          
           
               
                   
                 (kcal/mole) 
                 (kJ/mol) 
               
               
                   
                   
               
             
          
           
               
                 Relevant oxides 
                   
                   
               
               
                 SiO 2  + H 2 O → H 2 SiO 3   
                 5.6 
                 23.4 
               
               
                 (vitreous silica) 
               
               
                 Al 2 O 3  + 3H 2 O → 2Al(OH) 3   
                 3.1 
                 13.0 
               
               
                 MgO + H 2 O → Mg(OH) 2   
                 −6.5 
                 −27.2 
               
               
                 CaO + H 2 O → Ca(OH) 2   
                 −13.1 
                 −54.8 
               
               
                 SrO + H 2 O → Sr(OH) 2   
                 −17.3 
                 −72.4 
               
               
                 Na 2 O + H 2 O → 2NaOH 
                 −33.5 
                 −140.2 
               
               
                 K 2 O + H 2 O → 2KOH 
                 −46.1 
                 −192.9 
               
               
                 TiO 2  + H 2 O → Ti(OH) 2 O 
                 16.0 
                 66.9 
               
               
                 P 2 O 5  + 3H 2 O → 2H 3 PO 4   
                 −55.9 
                 −233.9 
               
               
                 B 2 O 3  + 3H 2 O → 2H 3 BO 3   
                 −9.8 
                 −41.0 
               
               
                 ZrO 2  + H 2 O → Zr(OH) 2 O 
                 −7.1 
                 −29.7 
               
               
                 Relevant Silicates 
               
               
                 Na 2 SiO 3  + 2H + (aq) → H 2 SiO 3  + 2Na + (aq) 
                 −28.8 
                 −120.5 
               
               
                 K 2 SiO 3  + 2H + (aq) → H 2 SiO 3  + 2K + (aq) 
                 −41.7 
                 −174.5 
               
               
                 MgSiO 3  + 2H + (aq) → H 2 SiO 3  + Mg 2+ (aq) 
                 −13.9 
                 −58.2 
               
               
                 CaSiO 3  + 2H + (aq) → H 2 SiO 3  + Ca 2+ (aq) 
                 −16.1 
                 −67.4 
               
               
                 SrSiO 3  + 2H + (aq) → H 2 SiO 3  + Sr 2+ (aq) 
                 −24.4 
                 −102.1 
               
               
                 BaSiO 3  + 2H + (aq) → H 2 SiO 3  + Ba 2+ (aq) 
                 −37.3 
                 −156.1 
               
               
                 ZnSiO 3  + 2H + (aq) → H 2 SiO 3  + Zn 2+ (aq) 
                 −2.4 
                 −10.0 
               
               
                 Disilicates 
               
               
                 Ca 2 SiO 4  + 3H + (aq) → H 2 SiO 3  + 2Ca 2+ + OH −   
                 −30.3 
                 −126.8 
               
               
                 Sr 2 SiO 4  + 3H + (aq) → H 2 SiO 3  + 2Sr 2+  + OH −   
                 −50.3 
                 −210.5 
               
               
                 Mg 2 SiO 4  + 3H + (aq) → H 2 SiO 3  + 2Mg 2+  + OH −   
                 −17.9 
                 −74.9 
               
               
                   
               
             
          
         
       
     
     Although calculations were undertaken assuming the presence of the simplest silicates choice of other silicates (such as disilicates) does not appear to change the calculations much. For example given below is the calculation for an assumed composition which shows only minor differences for the free energy of hydration calculated. 
     
       
         
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
               
             
             
               
                 Composition (moles/100 g) 
                 0.767 CaO 
               
               
                   
                 0.417 MgO 
               
               
                   
                 0.669 SiO 2   
               
             
          
           
               
                 0.384 Ca 2 SiO 4   
                 = 
                 −11.6 
                 or 
                 0.433 CaSiO 3   
                 = 
                 −7.0 
               
               
                 0.285 MgSiO 3   
                 = 
                 −4.0 
                   
                 0.236 MgSiO 3   
                 = 
                 −3.3 
               
               
                 0.132 MgO 
                 = 
                 −0.9 
                   
                 0.334 CaO 
                 = 
                 −4.4 
               
               
                   
                   
                 −16.5 
                   
                 0.181 MgO 
                 = 
                 −1.2 
               
               
                   
                   
                   
                   
                   
                   
                 −15.9 
               
               
                   
                   
                   
                 or 
                 0.384 Ca 2 SiO 4   
                 = 
                 −11.6 
               
               
                   
                   
                   
                   
                 0.132 Mg 2 SiO 4   
                 = 
                 −2.4 
               
               
                   
                   
                   
                   
                 0.153 MgSiO 3   
                 = 
                 −2.1 
               
               
                   
                   
                   
                   
                   
                   
                 −16.1 
               
               
                   
               
             
          
         
       
     
     The applicants have found that when the free energy of hydration is more negative than −10 kcal/100 grams (−418.4 kJ/kg) of composition the composition showed high solubility. The compositions where this relationship broke down were those for which the total solubility was not available (for example those materials containing sodium, where any dissolved sodium would be swamped by the sodium in the saline solution) or where the free energy of hydration of the most likely species present was not available from the literature. 
     As a test of this technique the two examples of European Patent No. 0399320 were examined. The disclosed examples had the compositions:— 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                   
                 Composition 1 
                 Composition 2 
               
               
                   
                 Component 
                 Weight percent 
                 Weight percent 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 SiO 2   
                 60.7 
                 58.5 
               
               
                   
                 Al 2 O 3   
                 — 
                 5.8 
               
               
                   
                 CaO 
                 16.5 
                 3.0 
               
               
                   
                 MgO 
                 3.2 
                 — 
               
               
                   
                 B 2 O 3   
                 3.3 
                 11.0 
               
               
                   
                 Na 2 O 
                 15.4 
                 9.8 
               
               
                   
                 K 2 O 
                 0.7 
                 2.9 
               
               
                   
                 Iron oxide 
                 0.2 
                 0.1 
               
               
                   
                 BaO 
                 — 
                 5.0 
               
               
                   
                 ZnO 
                 — 
                 3.9 
               
               
                   
                   
               
             
          
         
       
     
     Using the above method of calculation Composition 1 had a free energy of hydration of −11.6 kcal/100 grams (−485.3 kJ/kg) whereas Composition 2 had a free energy of hydration of −5.8 kcal/100 grams (−242.6 kJ/kg). This would suggest that composition 1 would be a saline soluble fibre, and hence physiologically safer than an insoluble fibre; whereas Composition 2 would be predicted to be a relatively insoluble fibre and hence less safe. This is what is disclosed in EP 0399320, the fibres of Composition 2 having a longer lifetime in studies in which the fibres were introduced interperitoneally into rats. 
     As mentioned above this predictive test can fail under some circumstances. To avoid these difficulties the applicants looked to a different predictive technique, namely the assessment of the amount of non-bridging oxygens present. This is calculated by normalising the chemical analysis to 100 weight %; calculating the molar percentage of each oxide; summing the oxygen-weighted contribution of each oxide to get the total number of oxygens; summing the weighted contribution of each oxide of non-bridging oxygens (see below); and taking the ratio of non-bridging oxygens to the total number of oxygens. The applicants have found that when this figure exceeds 30% the fibres are soluble. 
     To explain the term non-bridging oxygen one must look to the structure of glasses. Glasses are very stiff liquids and to form usually require the presence of a material that can form a network (usually an oxygen-bridged network). The network may be modified by constituents that contribute non-bridging parts to the network and open the structure of the network and so prevent crystallisation. These materials are usually referred to as network-formers and modifiers respectively. 
     The terms modifier and network former are well known in the glass industries. Network formers are materials such as SiO 2 , P 2 O 5 , B 2 O 3  and GeO 2  which can form an interconnected network to form the glassy phase. Modifiers are substances such as CaO, Na 2 O, and K 2 O which alter the network and have effects on such properties as viscosity and melting point. There are some intermediate materials (such as Al 2 O 3 , TiO 2 , PbO, ZnO and BeO) which can act as both network formers and modifiers depending on the environment and on the amount present. 
     In the above mentioned test, for calculating the non-bridging oxygens, one ignores the network formers and calculates the contribution of each other oxide. The contribution of each oxide depends on the geometry and charge of each cation in the glass. As examples typical contributions are as follows:— 
     Ca 2+ , Mg 2+ , Sr 2+  and other divalent network modifier cations contribute 2 non-bridging oxygens 
     K + , Na +  and other monovalent network modifier cations contribute 1 non-bridging oxygen 
     Al 3+ , Ti 3+  and other intermediate cations contribute −1 non-bridging oxygen (i.e these oxides reduce the number of non-bridging oxygens) 
     (Ti 4+  is reduced to Ti 3+  in most glasses when present in relatively small quantities) 
     
       
         
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 13 
               
             
             
               
                   
                   
               
               
                   
                 Composition 
                   
                 Mol. 
                 Oxygen 
                   
                 % 
                 Solubility 
                 S.S.A 
                 Normalized 
                 Log 
               
             
          
           
               
                 Melt Code 
                 Oxide 
                 Wt. % 
                 Moles 
                 % 
                 Total 
                 N.B.O 
                 N.B.O 
                 Oxide 
                 (ppm) 
                 m2/g 
                 Solubility 
                 (norm solub) 
               
               
                   
               
             
          
           
               
                 CAS10(B) - 
                 CaO 
                 47.2 
                 0.842 
                 54.9 
                 160.8 
                 78.4 
                 48.8 
                 CaO 
                 44 
                 0.30 
                 43 
                 1.63 
               
               
                 A 
                 Al2O3 
                 24.5 
                 0.240 
                 15.7 
                   
                   
                   
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 27.1 
                 0.451 
                 29.4 
                   
                   
                   
                 SiO2 
                 7 
               
               
                   
                   
                 Total 
                 1.533 
                 100.0 
                   
                   
                   
                 Total 
                 51 
               
               
                 CAS10(B) - 
                 CaO 
                 46.5 
                 0.829 
                 54.0 
                 160.9 
                 77.8 
                 48.4 
                 CaO 
                 58 
                 0.39 
                 66 
                 1.82 
               
               
                 B 
                 Al2O3 
                 23.7 
                 0.232 
                 15.1 
                   
                   
                   
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 28.4 
                 0.473 
                 30.8 
                   
                   
                   
                 SiO2 
                 44 
               
               
                   
                   
                 Total 
                 1.534 
                 100.0 
                   
                   
                   
                 Total 
                 103 
               
               
                 CAS10(B) - 
                 CaO 
                 47.8 
                 0.852 
                 55.4 
                 159.6 
                 80.4 
                 50.4 
                 CaO 
                 55 
                 0.36 
                 76 
                 1.88 
               
               
                 C 
                 Al2O3 
                 23.9 
                 0.234 
                 15.2 
                   
                   
                   
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 21.1 
                 0.451 
                 29.3 
                   
                   
                   
                 SiO2 
                 55 
               
               
                   
                   
                 Total 
                 1.537 
                 100.0 
                   
                   
                   
                 Total 
                 110 
               
               
                 CIS(A) 
                 CaO 
                 42.7 
                 0.761 
                 47.5 
                 152.5 
                 85.1 
                 55.8 
                 CaO 
                 62 
                 0.40 
                 69 
                 1.84 
               
               
                   
                 TiO2 
                 12.7 
                 0.159 
                 9.9 
                   
                   
                   
                 TiO2 
                 0 
               
               
                   
                 SiO2 
                 41.0 
                 0.682 
                 42.6 
                   
                   
                   
                 SiO2 
                 49 
               
               
                   
                   
                 Total 
                 1.602 
                 100.0 
                   
                   
                   
                 Total 
                 111 
               
               
                 SrSiO3 
                 SrO 
                 63.1 
                 0.609 
                 51.2 
                 148.8 
                 102.4 
                 68.8 
                 SrO 
                 2 
                 0.37 
                 249 
                 2.40 
               
               
                   
                 SiO2 
                 34.9 
                 0.581 
                 48.8 
                   
                   
                   
                 SiO2 
                 367 
               
               
                   
                   
                 Total 
                 1.190 
                 100.0 
                   
                   
                   
                 Total 
                 369 
               
               
                 CaSiO3 
                 CaO 
                 46.1 
                 0.822 
                 48.6 
                 151.4 
                 97.2 
                 64.2 
                 CaO 
                 41 
                 0.45 
                 163 
                 2.21 
               
               
                   
                 SiO2 
                 52.3 
                 0.870 
                 51.4 
                   
                   
                   
                 SiO2 
                 253 
               
               
                   
                   
                 Total 
                 1.692 
                 100.0 
                   
                   
                   
                 Total 
                 294 
               
               
                 NAS(A) 
                 Na2O 
                 18.8 
                 0.303 
                 22.0 
                 228.3 
                 −12.6 
                 −5.5 
                 Na2O 
                 # 
                 0.56 
                 4 
                 0.60 
               
               
                   
                 Al2O3 
                 39.7 
                 0.389 
                 28.3 
                   
                   
                   
                 Al2O3 
                 4 
               
               
                   
                 SiO2 
                 41.1 
                 0.684 
                 49.7 
                   
                   
                   
                 SiO2 
                 5 
               
               
                   
                   
                 Total 
                 1.376 
                 100.0 
                   
                   
                   
                 Total 
                 9 
               
               
                 CAS4 
                 CaO 
                 21.0 
                 0.374 
                 25.7 
                 198.1 
                 3.8 
                 1.9 
                 CaO 
                 11 
                 0.62 
                 8 
                 0.90 
               
               
                   
                 Al2O3 
                 35.4 
                 0.347 
                 23.8 
                   
                   
                   
                 Al2O3 
                 4 
               
               
                   
                 SiO2 
                 44.2 
                 0.736 
                 50.5 
                   
                   
                   
                 SiO2 
                 5 
               
               
                   
                   
                 Total 
                 1.457 
                 100.0 
                   
                   
                   
                 Total 
                 20 
               
               
                 MAS(B) 
                 MgO 
                 10.0 
                 0.248 
                 17.0 
                 205.6 
                 −11.2 
                 −5.4 
                 MgO 
                 7 
                 0.52 
                 6 
                 0.78 
               
               
                   
                 Al2O3 
                 33.7 
                 0.331 
                 22.6 
                   
                   
                   
                 Al2O3 
                 2 
               
               
                   
                 SiO2 
                 53.0 
                 0.882 
                 60.4 
                   
                   
                   
                 SiO2 
                 4 
               
               
                   
                   
                 Total 
                 1.461 
                 100.0 
                   
                   
                   
                 Total 
                 13 
               
               
                 SAS(A) 
                 SrO 
                 29.8 
                 0.288 
                 23.9 
                 201.4 
                 −2.6 
                 −1.4 
                 SrO 
                 9 
                 0.50 
                 8 
                 0.90 
               
               
                   
                 Al2O3 
                 31.1 
                 0.305 
                 25.3 
                   
                   
                   
                 Al2O3 
                 2 
               
               
                   
                 SiO2 
                 36.8 
                 0.612 
                 50.8 
                   
                   
                   
                 SiO2 
                 5 
               
               
                   
                   
                 Total 
                 1.205 
                 100.0 
                   
                   
                   
                 Total 
                 16 
               
               
                 SCS(A) 
                 SrO 
                 35.0 
                 0.338 
                 23.5 
                 150.5 
                 99.0 
                 65.8 
                 SrO 
                 75 
                 0.41 
                 280 
                 2.45 
               
               
                   
                 CaO 
                 21.0 
                 0.374 
                 26.0 
                   
                   
                   
                 CaO 
                 30 
               
               
                   
                 SiO2 
                 43.6 
                 0.726 
                 50.5 
                   
                   
                   
                 SiO2 
                 355 
               
               
                   
                   
                 Total 
                 1.438 
                 100.0 
                   
                   
                   
                 Total 
                 460 
               
               
                 SMAS(A) 
                 SrO 
                 55.0 
                 0.531 
                 49.1 
                 169.6 
                 60.8 
                 35.8 
                 SrO 
                 57 
                 0.46 
                 38 
                 1.58 
               
               
                   
                 MgO 
                 1.2 
                 0.030 
                 2.8 
                   
                   
                   
                 MgO 
                 5 
               
               
                   
                 Al2O3 
                 23.7 
                 0.232 
                 21.5 
                   
                   
                   
                 Al2O3 
                 2 
               
               
                   
                 SiO2 
                 17.3 
                 0.288 
                 26.6 
                   
                   
                   
                 SiO2 
                 5 
               
               
                   
                   
                 Total 
                 1.081 
                 100.0 
                   
                   
                   
                 Total 
                 69 
               
               
                 SMAS(B) 
                 SrO 
                 55.0 
                 0.531 
                 44.6 
                 157.6 
                 84.8 
                 53.8 
                 SrO 
                 110 
                 0.39 
                 95 
                 1.98 
               
               
                   
                 MgO 
                 4.8 
                 0.119 
                 10.0 
                   
                   
                   
                 MgO 
                 15 
               
               
                   
                 Al2O3 
                 14.8 
                 0.145 
                 12.2 
                   
                   
                   
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 23.7 
                 0.394 
                 33.2 
                   
                   
                   
                 SiO2 
                 22 
               
               
                   
                   
                 Total 
                 1.189 
                 100.0 
                   
                   
                   
                 Total 
                 148 
               
               
                 SMS(A) 
                 SrO 
                 33.0 
                 0.318 
                 20.7 
                 159.5 
                 80.6 
                 50.5 
                 SrO 
                 147 
                 0.39 
                 212 
                 2.33 
               
               
                   
                 MgO 
                 12.5 
                 0.310 
                 20.2 
                   
                   
                   
                 MgO 
                 61 
               
               
                   
                 Al2O3 
                 1.0 
                 0.010 
                 0.6 
                   
                   
                   
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 53.8 
                 0.895 
                 58.4 
                   
                   
                   
                 SiO2 
                 123 
               
               
                   
                   
                 Total 
                 1.533 
                 100.0 
                   
                   
                   
                 Total 
                 331 
               
               
                 SAS(C) 
                 SrO 
                 56.0 
                 0.540 
                 47.7 
                 169.3 
                 61.4 
                 36.3 
                 SrO 
                 70 
                 0.38 
                 52 
                 1.72 
               
               
                   
                 Al2O3 
                 19.7 
                 0.193 
                 17.0 
                   
                   
                   
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 24.0 
                 0.399 
                 35.3 
                   
                   
                   
                 SiO2 
                 8 
               
               
                   
                   
                 Total 
                 1.132 
                 100.0 
                   
                   
                   
                 Total 
                 79 
               
               
                 CMAS(A) 
                 CaO 
                 35.0 
                 0.624 
                 42.6 
                 179.3 
                 41.4 
                 23.1 
                 CaO 
                 11 
                 0.30 
                 24 
                 1.38 
               
               
                   
                 MgO 
                 4.5 
                 0.112 
                 7.6 
                   
                   
                   
                 MgO 
                 7 
               
               
                   
                 Al2O3 
                 44.0 
                 0.432 
                 29.5 
                   
                   
                   
                 Al2O3 
                 3 
               
               
                   
                 SiO2 
                 17.8 
                 0.296 
                 20.3 
                   
                   
                   
                 SiO2 
                 8 
               
               
                   
                   
                 Total 
                 1.464 
                 100.0 
                   
                   
                   
                 Total 
                 29 
               
               
                 SWA2 
                 CaO 
                 21.7 
                 0.387 
                 21.4 
                 157.5 
                 85.0 
                 54.0 
                 CaO 
                 53 
                 0.48 
                 119 
                 2.08 
               
               
                   
                 MgO 
                 15.7 
                 0.389 
                 21.5 
                   
                   
                   
                 MgO 
                 57 
               
               
                   
                 Al2O3 
                 0.8 
                 0.008 
                 0.4 
                   
                   
                   
                 Al2O3 
                 0 
               
               
                   
                 SiO2 
                 61.8 
                 1.028 
                 56.7 
                   
                   
                   
                 SiO2 
                 118 
               
               
                   
                   
                 Total 
                 1.812 
                 100.0 
                   
                   
                   
                 Total 
                 228 
               
               
                 SAS(D) 
                 SrO 
                 56.5 
                 0.545 
                 48.5 
                 166.9 
                 66.2 
                 39.7 
                 SrO 
                 107 
                 0.40 
                 92 
                 1.96 
               
               
                   
                 Al2O3 
                 17.6 
                 0.173 
                 15.4 
                   
                   
                   
                 Al2O3 
               
               
                   
                 SiO2 
                 24.4 
                 0.406 
                 36.1 
                   
                   
                   
                 SiO2 
                 39 
               
               
                   
                   
                 Total 
                 1.124 
                 100.0 
                   
                   
                   
                 Total 
                 147 
               
               
                 KMAS(A) 
                 K2O 
                 16.5 
                 0.175 
                 11.3 
                 179.5 
                 41.4 
                 23.1 
                 K2O 
                 # 
                 0.36 
                 14 
                 1.15 
               
               
                   
                 MgO 
                 13.0 
                 0.323 
                 20.8 
                   
                   
                   
                 MgO 
                 8 
               
               
                   
                 Al2O3 
                 18.0 
                 0.177 
                 11.4 
                   
                   
                   
                 Al2O3 
                 1 
               
               
                   
                 SiO2 
                 52.8 
                 0.879 
                 56.6 
                   
                   
                   
                 SiO2 
                 11 
               
               
                   
                   
                 Total 
                 1.554 
                 100.0 
                   
                   
                   
                 Total 
                 20 
               
               
                   
               
             
          
         
       
     
     Table 13 shows, for the compositions of Table 11, the calculated figure for non-bonding oxygens and these figures are reproduced in  FIG. 5 . It can be seen that the plot of  FIG. 5  is more linear than that of  FIG. 4 . Compositions with greater than 30% non-bridging oxygens show high solubility. 
     To illustrate the method the calculation for one example (the first shown in Table 13) is given below:— 
     
       
         
               
               
               
               
             
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Mols/ 
                 Total 
                 Non-bridging 
               
               
                   
                 Mol 
                 Oxygen 
                 Oxygens 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 CaO 
                 0.549 
                 0.549 
                   1.098 (2 * 0.549) 
               
               
                 Al 2 O 3   
                 0.157 
                 0.471 (0.157 * 3) 
                 −0.314 (−1 * 0.157 * 2A1) 
               
               
                 SiO 2   
                 0.294 
                 0.588 
                   0.000 
               
               
                   
                 1.000 
                 1.608 
                  0.784 
               
               
                   
               
               
                 % non-bridging oxygens (0.784/1.608) * 100 = 48.8% 
               
             
          
         
       
     
     As an example one can look to European Patent Specification No. 0399320 referred to above. Using this method in relation to that specification Composition 1 has a non-bridging oxygen percentage of 48.2% whereas Composition 2 has a non-bridging oxygen percentage of 19.6%, again predicting that Composition 1 is more soluble than Composition 2. 
     There is a further criterion which a composition must meet for it to form vitreous fibres, namely that it be capable of forming a glass. The applicants have found a simple test. If the ratio of modifiers to network formers is less than a critical value (for SiO 2  based glasses, 1) the composition will generally form a glass. For the purpose of this test reasonable results are obtained if such intermediate materials are treated as networkers. Table 14 shows for a series of compositions in each column:—
         Fibre reference (N.B. these are not the same fibres as shown in tables 9 &amp; 10)   Composition   Molar ratios   Ratio of glass modifiers to network formers   Free energy of hydration of raw oxides   Melting Point   X-ray diffraction results   Solubility data (# indicates not measured)   Specific surface area   Normalised solubility data   Arbitrary ranking as to solubility and glass forming ability   Indication as to whether melting point above 1500° C.       

     It should be emphasised that this test is a screening one rather than a wholly predictive one as there are several circumstances that may lead to its failure. Among these circumstances are compound formation and inability to quench fast enough to form glass. 
     Having adopted these tests as a screening method there follows a further step to ascertain whether the composition will form a vitreous fibre. This last step is best examined experimentally as fibre forming ability is a complex function of many physical characteristics, e.g. viscosity, which are often difficult to measure. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Key to FIG. 1 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 CR Cristobalite 
                 FO Forsterite 
               
               
                   
                 TR Tridymite 
                 PR Protoenstatite 
               
               
                   
                 PS Pseudowollastonite 
                 DI Diopside 
               
               
                   
                 WO Wollastonite 
                 AK Akermanite 
               
               
                   
                 RA Rankinite 
                 ME Merwinite 
               
               
                   
                 LI Lime 
                 MO Monticellite 
               
               
                   
                 PE Periclase 
               
               
                   
                   
               
             
          
         
       
     
     
       
         
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 14 
               
             
             
               
                   
                   
               
               
                   
                   
                   
                   
                   
                   
                   
                   
                   
                 Norm Solub 
                 Criteria 
                   
               
               
                   
                 Composition 
                   
                 Modifier/ 
                   
                   
                   
                 Solubility Data (ppm) 
                 S.S.A. 
                 (0.25 m2/g) 
                 (0–10 Rating) 
                 M. Pt. 
               
             
          
           
               
                 Reference 
                 (Wt. %) 
                 Molar Ratios 
                 Networker 
                 Ghyd (kcal/mol) 
                 M. Pt. (C.) 
                 % RD Data 
                 Species 
                 1 day 
                 Total 
                 5 days 
                 Total 
                 (m2/g) 
                 1 day 
                 5 days 
                 Solub 
                 Glass 
                 &gt;1500 C. 
               
               
                   
               
             
          
           
               
                 CAS10(A) 
                 49.4 CaO 
                  3.8 CaO 
                 0.97 
                   
                 1544 
                 Amorphous * trace 
                 CaO 
                 62 
                   
                 48 
                   
                 0.25 
                 124 
                 187 
                 10 
                 9 
                 T 
               
               
                 No. 18 
                 23.4 Al2O3 
                  1.0 Al2O3 
                   
                 −4.6 
                 (Eut.) 
                 (3 small peaks) 
                 Al2O3 
                 7 
                 124 
                 10 
                 182 
               
               
                   
                 29.2 SiO2 
                  1.9 SiO2 
                   
                   
                   
                   
                 SiO2 
                 55 
                   
                 124 
               
               
                   
               
               
                 CIS(A) 
                 42.7 CaO 
                  4.7 CaO 
                 0.85 
                   
                 1425 
                 Amorphous 
                 CaO 
                 100 
                   
                 88 
                   
                 0.56 
                 83 
                 88 
                 7 
                 10 
                 W 
               
               
                 No. 19 
                 13.0 TiO2 
                  1.0 TiO2 
                   
                 −1.3 
                 (Eut.) 
                 (No peaks) 
                 TiO2 
                 0 
                 187 
                 0 
                 197 
               
               
                   
                 43.6 SiO2 
                  4.5 SiO2 
                   
                   
                   
                   
                 SiO2 
                 87 
                   
                 109 
               
               
                 MAS(A) 
                 12.4 MgO 
                  1.2 MgO 
                 0.2 
                   
                 1450 
                 Amorphous * trace 
                 MgO 
                 63 
                   
                 248 
                   
                 0.57 
                 40 
                 116 
                 4 
                 9 
                 W 
               
               
                 No. 20 
                 26.5 Al2O3 
                  1.0 Al2O3 
                   
                 3.8 
                 (1400 C.) 
                 (2 small peaks) 
                 Al2O3 
                 5 
                 92 
                 1 
                 264 
               
               
                   
                 62.4 SiO2 
                   40 SiO2 
                   
                   
                   
                   
                 SiO2 
                 24 
                   
                 15 
               
               
                 MAS(A) 
                 29.4 Na2O 
                  1.2 Na2O 
                 0.69 
                   
                 1475 
                 Crystalline 
                 Na2O 
                 # 
                   
                 # 
                   
                 0.53 
                 15 
                 471 
                 1 
                 2 
                 W 
               
               
                 No. 21 
                 39.2 Al2O3 
                  1.0 Al2O3 
                   
                 −6.3 
                 (Eut.) 
                 (Glossy trace) 
                 Al2O3 
                 3 
                 37 
                 983 
                 990 
               
               
                   
                 33.7 SiO2 
                  1.5 SiO2 
                   
                   
                   
                   
                 SiO2 
                 29 
                   
                 15 
               
               
                   
               
               
                 CPI(A) 
                 53.3 CaO 
                  2.7 CaO 
                 1.35 
                 −24.7 
                 1565 
                 Crystalline 
                 CaO 
                 47 
                 47 
                 17 
                 17 
                 0.68 
                 17 
                 6 
                 1 
                 0 
                 T 
               
               
                 No. 22 
                 50.6 P2O5 
                  1.0 P2O5 
                   
                   
                 (Eut.) 
                 (No glass) 
                 P2O5 
                 # 
                   
                 # 
               
               
                 SAI(B) 
                 68.0 SiO 
                  1.1 SiO 
                 1.1 
                 −5.7 
                 1545 
                 Amorphous (strong) * 
                 SiO 
                 11 
                 1247 
                 5 
                 729 
                 0.88 
                 346 
                 203 
                 10 
                 5 
                 T 
               
               
                 No. 23 
                 35.9 SiO2 
                  1.0 SiO2 
                   
                   
                 (Eut.) 
                 some crystal. (strong) 
                 SiO2 
                 1236 
                   
                 724 
               
               
                 CaSiO3 
                 42.3 CaO 
                  1.0 CaO 
                 0.77 
                 −3 
                 1545 
                 Amorphous * trace 
                 CaO 
                 19 
                 1284 
                 27 
                 508 
                 0.71 
                 452 
                 179 
                 10 
                 9 
                 T 
               
               
                 No. 24 
                 57.2 SiO2 
                  1.3 SiO2 
                   
                   
                 (1460 C.) 
                 (3 small peaks) 
                 SiO2 
                 1265 
                   
                 481 
               
               
                 ASI(D) 
                 37.3 MgO 
                  1.0 MgO 
                 0.91 
                 0.6 
                 1545 
                 Crystalline (strong) * 
                 MgO 
                 62 
                 216 
                 249 
                 362 
                 0.83 
                 65 
                 127 
                 5 
                 6 
                 T 
               
               
                 No. 26 
                 62.5 SiO2 
                  1.1 SiO2 
                   
                   
                 (Eut.) 
                 some glass (strong) 
                 SiO2 
                 154 
                   
                 113 
               
               
                 C612A17 
                 47.7 CaO 
                 11.2 CaO 
                 0.8 
                 −7.2 
                 1400 
                 Amorphous * trace 
                 CaO 
                 14 
                 317 
                 3 
                 145 
                 2.45 
                 37 
                 15 
                 3 
                 7 
                 W 
               
               
                 No. 28 
                 53.9 Al2O3 
                  7.0 Al2O3 
                   
                   
                 (Eut.) 
                 (Mod. cryst.) 
                 Al2O3 
                 298 
                   
                 142 
               
               
                   
               
               
                 CMS(A) 
                 42.5 CaO 
                  1.8 CaO 
                 7 
                   
                 1575 
                 Crystalline 
                 CaO 
                 42 
                   
                 21 
                   
                 0.47 
                 158 
                 118 
                 10 
                 0 
                 T 
               
               
                 No. 27 
                 16.6 MgO 
                  1.0 MgO 
                   
                 −4.3 
                 (Eut.) 
                 (No glass) 
                 MgO 
                 41 
                 303 
                 8 
                 227 
               
               
                   
                 39.7 SiO2 
                  1.4 SiO2 
                   
                   
                   
                   
                 SiO2 
                 220 
                   
                 198 
               
               
                 CTI(D) 
                 15.4 CaO 
                  1.0 CaO 
                 4.570 
                 9.5 
                 1465 
                 Crystalline 
                 CaO 
                 14 
                 14 
                 16 
                 16 
                 1.15 
                 3 
                 3 
                 0 
                 0 
                 W 
               
               
                 No. 25 
                 77.5 TiO2 
                  3.5 TiO2 
                   
                   
                 (Eut.) 
                 (No glass) 
                 TiO2 
                 0 
                   
                 0 
               
               
                 NCS(A) 
                 20.4 Na2O 
                  1.0 Na2O 
                 1.86 
                   
                 1425 
                 Crystalline * 
                 Na2O 
                 # 
                   
                 # 
                   
                 0.99 
                 204 
                 95 
                 10 
                 4 
                 W 
               
               
                 Cryst. 
                 35.8 CaO 
                  1.9 CaO 
                   
                 −8.7 
                 (Eut.) 
                 some glass 
                 CaO 
                 595 
                 806 
                 333 
                 375 
               
               
                 No. 29 
                 40.8 SiO2 
                  2.1 SiO2 
                   
                   
                   
                 (Strong cryst.) 
                 SiO2 
                 211 
                   
                 42 
               
               
                 NCS(A) 
                 19.5 Na2O 
                  1.0 Na2O 
                 1.74 
                   
                 1425 
                 Amorphous * 
                 Na2O 
                 # 
                   
                 # 
                   
                 1.36 
                 123 
                 49 
                 10 
                 7 
                 W 
               
               
                 Glassy 
                 35.3 CaO 
                  2.0 CaO 
                   
                 −8.1 
                 (Eut.) 
                 some crystal. 
                 CaO 
                 543 
                 686 
                 237 
                 271 
               
               
                 No. 30 
                 42.7 SiO2 
                  2.3 SiO2 
                   
                   
                   
                 (8 small peaks) 
                 SiO2 
                 143 
                   
                 34 
               
               
                 CPI(A)Rpt 
                 54.4 CaO 
                  2.9 CaO 
                 1.45 
                 −24 
                 1565 
                 Crystalline 
                 CaO 
                 14 
                 14 
                 13 
                 13 
                 1.04 
                 3 
                 3 
                 0 
                 0 
                 T 
               
               
                 No. 31 
                 48.2 P2O5 
                  1.0 P2O5 
                   
                   
                 (Eut.) 
                 (No glass) 
                 P2O5 
                 # 
                   
                 # 
               
               
                   
               
               
                 NAS(A) 
                 21.0 Na2O 
                  1.0 Na2O 
                 0.48 
                   
                 1475 
                 Amorphous 
                 Na2O 
                 # 
                   
                 # 
                   
                 0.53 
                 17 
                 24 
                 1 
                 10 
                 W 
               
               
                 Apt. 
                 40.1 Al2O3 
                  1.2 Al2O3 
                   
                 −4 
                 (Eut.) 
                 (No peaks) 
                 Al2O3 
                 18 
                 37 
                 30 
                 50 
               
               
                 No. 32 
                 38.7 SiO2 
                  1.8 SiO2 
                   
                   
                   
                   
                 SiO2 
                 19 
                   
                 20 
               
               
                 KAS(E) 
                 20.0 K2O 
                  1.0 K2O 
                 0.31 
                   
                 1590 
                 Amorphous 
                 K2O 
                 # 
                   
                 # 
                   
                 0.97 
                 7 
                 10 
                 1 
                 10 
                 T 
               
               
                 No. 33 
                 30.4 Al2O3 
                  1.4 Al2O3 
                   
                 −2.7 
                 (Eut.) 
                 (No peaks) 
                 Al2O3 
                 9 
                 28 
                 18 
                 39 
               
               
                   
                 46.1 SiO2 
                  3.6 SiO2 
                   
                   
                   
                   
                 SiO2 
                 19 
                   
                 21 
               
               
                 CAS4 
                 21.2 CaO 
                  1.1 CaO 
                 0.26 
                   
                 1550 
                 Amorphous 
                 CaO 
                 17 
                   
                 13 
                   
                 0.72 
                 10 
                 8 
                 1 
                 10 
                 T 
               
               
                 No. 34 
                 34.0 Al2O3 
                  1.0 Al2O3 
                   
                 1.1 
                 (1500 C.) 
                 (No peaks) 
                 Al2O3 
                 1 
                 28 
                 1 
                 24 
               
               
                   
                 44.6 SiO2 
                  2.2 SiO2 
                   
                   
                   
                   
                 SiO2 
                 10 
                   
                 10 
               
               
                   
               
               
                 NAS(D) 
                 14.9 MgO 
                  2.7 MgO 
                 0.24 
                   
                 1450 
                 Amorphous 
                 MgO 
                 7 
                   
                 68 
                   
                 0.61 
                 6 
                 42 
                 1 
                 10 
                 W 
               
               
                 No. 35 
                 35.9 Al2O3 
                  2.0 Al2O3 
                   
                 3.4 
                 (1400 C.) 
                 (No peaks) 
                 Al2O3 
                 1 
                 1.5 
                 24 
                 107 
               
               
                   
                 51.6 SiO2 
                  4.9 SiO2 
                   
                   
                   
                   
                 SiO2 
                 7 
                 20 
               
               
                 SAS(A) 
                 32.5 SiO 
                  1.0 SiO 
                 0.25 
                   
                 1670 
                 Amorphous 
                 SiO 
                 24 
                   
                 1 
                   
                 0.67 
                 19 
                 4 
                 2 
                 10 
                 T 
               
               
                 No. 36 
                 32.4 Al2O3 
                  1.0 Al2O3 
                   
                 0.1 
                 (7) 
                 (No peaks) 
                 Al2O3 
                 11 
                 50 
                 1 
                 12 
               
               
                   
                 38.1 SiO2 
                  2.0 SiO2 
                   
                   
                   
                   
                 SiO2 
                 15 
                   
                 10 
               
               
                 SCS(A) 
                 17.1 SiO 
                  1.1 SiO 
                 0.91 
                   
                 1480 
                 Amorphous * trace 
                 SiO 
                 57 
                   
                 3 
                   
                 0.57 
                 177 
                 258 
                 10 
                 10 
                 W 
               
               
                 No. 37 
                 17.5 CaO 
                  1.0 CaO 
                   
                 −3.6 
                 (Eut) 
                 (2 small peaks) 
                 CaO 
                 35 
                 411 
                 2 
                 599 
               
               
                   
                 43.4 SiO2 
                  2.3 SiO2 
                   
                   
                   
                   
                 SiO2 
                 329 
                   
                 594 
               
               
                 SCS(C) 
                 19.5 SiO 
                  0.5 SiO 
                 0.9 
                   
                 1500 
                 Amorphous 
                 SiO 
                 55 
                   
                 11 
                   
                 0.66 
                 155 
                 219 
                 10 
                 10 
                 T 
               
               
                 No. 38 
                 29.4 CaO 
                  1.4 CaO 
                   
                 −3.1 
                 (Eut.) 
                 (No peaks) 
                 CaO 
                 36 
                 411 
                 10 
                 579 
               
               
                   
                 47.1 SiO2 
                  2.1 SiO2 
                   
                   
                   
                   
                 SiO2 
                 320 
                   
                 558 
               
               
                   
               
               
                 SCS(B) 
                 51.4 SiO 
                  1.7 SiO 
                 0.96 
                   
                 1500 
                 Amorphous * trace 
                 SiO 
                 5 
                   
                 45 
                   
                 0.66 
                 161 
                 219 
                 10 
                 10 
                 T 
               
               
                 No. 39 
                  8.1 CaO 
                  0.5 CaO 
                   
                 −4.6 
                 (Eut.) 
                 (1 small peak) 
                 CaO 
                 5 
                 425 
                 27 
                 579 
               
               
                   
                 39.7 SiO2 
                  2.3 SiO2 
                   
                   
                   
                   
                 SiO2 
                 415 
                   
                 507 
               
               
                 SAS(B) 
                 65.9 SiO 
                  5.2 SiO 
                 0.96 
                   
                 1600 
                 Crystalline (strong) * 
                 SiO 
                 102 
                   
                 5 
                   
                 0.99 
                 114 
                 65 
                 10 
                 5 
                 T 
               
               
                 No. 40 
                 12.4 Al2O3 
                  1.0 Al2O3 
                   
                 −6.6 
                 (7) 
                 some glass (strong) 
                 Al2O3 
                 1 
                 453 
                 1 
                 256 
               
               
                   
                 25.0 SiO2 
                  3.4 SiO2 
                   
                   
                   
                   
                 SiO2 
                 350 
                   
                 250 
               
               
                 SMAS(A) 
                 58.0 SiO 
                  2.7 SiO 
                 0.76 
                   
                 1610 
                 Amorphous * trace 
                 SiO 
                 87 
                   
                 61 
                   
                 0.65 
                 48 
                 31 
                 4 
                 10 
                 T 
               
               
                 No. 41 
                  1.1 MgO 
                  0.1 MgO 
                   
                 −6.7 
                 (1560 C.) 
                 (1 small peak) 
                 MgO 
                 7 
                 104 
                 4 
                 81 
               
               
                   
                 25.8 Al2O3 
                  0.9 Al2O3 
                   
                   
                   
                   
                 Al2O3 
                 1 
                   
                 1 
               
               
                   
                 18.4 SiO2 
                  1.1 SiO2 
                   
                   
                   
                   
                 SiO2 
                 9 
                   
                 15 
               
               
                 SMAS(B) 
                 59.1 SiO 
                  6.0 SiO 
                 0.91 
                   
                 1610 
                 Amorphous * trace 
                 SiO 
                 123 
                   
                 20 
                   
                 0.7 
                 70 
                 31 
                 6 
                 9 
                 T 
               
               
                 No. 42 
                  3.8 MgO 
                  1.0 MgO 
                   
                 −5.8 
                 (1500 C.) 
                 (3 small peaks) 
                 MgO 
                 32 
                 197 
                 29 
                 86 
               
               
                   
                 16.6 Al2O3 
                  1.7 Al2O3 
                   
                   
                   
                   
                 Al2O3 
                 1 
                   
                 1 
               
               
                   
                 24.6 SiO2 
                  4.3 SiO2 
                   
                   
                   
                   
                 SiO2 
                 41 
                   
                 36 
               
               
                   
               
               
                 SMS(A) 
                 35.9 SiO 
                  1.1 SiO 
                 0.78 
                   
                 1600 
                 Amorphous 
                 SiO 
                 159 
                   
                 42 
                   
                 0.75 
                 148 
                 176 
                 10 
                 10 
                 T 
               
               
                 No. 43 
                  0.8 Al2O3 
                   
                   
                 −0.4 
                 (1500 C.) 
                 (No peaks) 
                 MgO 
                 100 
                 444 
                 129 
                 348 
               
               
                   
                 12.9 MgO 
                  1.0 MgO 
                   
                   
                   
                   
                 SiO2 
                 185 
                   
                 177 
               
               
                   
                 51.2 SiO2 
                  2.7 SiO2 
               
               
                 SAS(C) 
                 60.6 SiO 
                  2.9 SiO 
                 0.74 
                   
                 1600 
                 Amorphous 
                 SiO 
                 142 
                   
                 104 
                   
                 0.67 
                 67 
                 50 
                 5 
                 10 
                 T 
               
               
                 No. 44 
                 20.7 Al2O3 
                  1.0 Al2O3 
                   
                 −5.9 
                 (7) 
                 (No peaks) 
                 Al2O3 
                 7 
                 167 
                 7 
                 133 
               
               
                   
                 22.6 SiO2 
                  1.9 SiO2 
                   
                   
                   
                   
                 SiO2 
                 18 
                   
                 22 
               
               
                 ACPS(A) 
                 16.6 Al2O3 
                  1.5 Al2O3 
                 0.74 
                   
                 1600 
                 Crystalline 
                 Al2O3 
                 1 
                   
                 1 
                   
                 0.58 
                 20 
                 19 
                 2 
                 0 
                 T 
               
               
                 No. 45 
                 39.0 CaO 
                  6.2 CaO 
                   
                 −17.7 
                 (Eut) 
                 (No glass) 
                 CaO 
                 39 
                 46 
                 35 
                 45 
               
               
                   
                 35.6 P2O5 
                  2.2 P2O5 
                   
                   
                   
                   
                 P2O5 
                 # 
                   
                 # 
               
               
                   
                  6.7 SiO2 
                  1.0 SiO2 
                   
                   
                   
                   
                 SiO2 
                 6 
                   
                 9 
               
               
                   
               
               
                 CMAS(A) 
                 30.6 CaO 
                  3.7 CaO 
                 0.6 
                   
                 1530 
                 Amorphous 
                 CaO 
                 24 
                   
                 21 
                   
                 0.54 
                 19 
                 18 
                 2 
                 10 
                 T 
               
               
                 No. 46 
                  5.9 MgO 
                  1.0 MgO 
                   
                 −3.2 
                 (Eut) 
                 (No peaks) 
                 MgO 
                 10 
                 40 
                 7 
                 39 
               
               
                   
                 41.6 Al2O3 
                  2.8 Al2O3 
                   
                   
                   
                   
                 Al2O3 
                 2 
                   
                 2 
               
               
                   
                 19.6 SiO2 
                  2.2 SiO2 
                   
                   
                   
                   
                 SiO2 
                 4 
                   
                 9 
               
               
                 SA 
                 69.1 SiO 
                  2.1 SiO 
                 1.05 
                 −10.7 
                 1500 
                 Crystalline (strong) * 
                 SiO 
                 49 
                 1155 
                 125 
                 1257 
                 0.62 
                 466 
                 507 
                 10 
                 4 
                 T 
               
               
                 No. 47 
                 32.2 Al2O3 
                  1.0 Al2O3 
                   
                   
                 (Eut) 
                 some glass (med) 
                 Al2O3 
                 1106 
                   
                 1132 
               
               
                 SW2A 
                 21.3 CaO 
                  1.0 CaO 
                 0.78 
                   
                 1360 
                 Amorphous 
                 CaO 
                 70 
                   
                 65 
                   
                 0.66 
                 127 
                 140 
                 10 
                 10 
                 W 
               
               
                 No. 48 
                 16.9 MgO 
                  1.1 MgO 
                   
                 −0.2 
                   
                 (No peaks) 
                 MgO 
                 91 
                 322 
                 116 
                 369 
               
               
                   
                  1.1 Al2O3 
                   
                   
                   
                   
                   
                 Al2O3 
                 10 
                   
                 1 
               
               
                   
                 61.5 SiO2 
                  2.7 SiO2 
                   
                   
                   
                   
                 SiO2 
                 151 
                   
                 187 
               
               
                 MAS(C) 
                 34.9 MgO 
                  3.5 MgO 
                 0.73 
                   
                 1600 
                 Amorphous (strong) * 
                 MgO 
                 50 
                   
                 135 
                   
                 0.52 
                 27 
                 67 
                 2 
                 7 
                 T 
               
               
                 No. 49 
                 25.5 Al2O3 
                  1.0 Al2O3 
                   
                 0 
                 (Eut) 
                 some cryst. (weak) 
                 Al2O3 
                 2 
                 58 
                 2 
                 144 
               
               
                   
                 41.7 SiO2 
                  2.3 SiO2 
                   
                   
                   
                   
                 SiO2 
                 7 
                   
                 7 
               
               
                   
               
               
                 SAS(D) 
                 60.3 SiO 
                  3.6 SiO 
                 0.84 
                   
                 1600 
                 Amorphous * trace 
                 SiO 
                 141 
                   
                 77 
                   
                 0.54 
                 123 
                 117 
                 10 
                 10 
                 T 
               
               
                 No. 50 
                 16.5 Al2O3 
                  1.0 Al2O3 
                   
                 −6.1 
                 (7) 
                 (2 peaks) 
                 Al2O3 
                 1 
                 260 
                 1 
                 249 
               
               
                   
                 22.4 SiO2 
                  2.3 SiO2 
                   
                   
                   
                   
                 SiO2 
                 118 
                   
                 171 
               
               
                 KMAS(A) 
                 17.5 K2O 
                  1.0 K2O 
                 0.56 
                   
                 1500 
                 Amorphous 
                 K2O 
                 # 
                   
                 # 
                   
                 0.94 
                 6 
                 7 
                 1 
                 10 
                 T 
               
               
                 No. 51 
                 13.5 MgO 
                  1.8 MgO 
                   
                 −2.4 
                 (Eut) 
                 (No peaks) 
                 MgO 
                 13 
                 23 
                 14 
                 25 
               
               
                   
                 18.6 Al2O3 
                  1.0 Al2O3 
                   
                   
                   
                   
                 Al2O3 
                 1 
                   
                 1 
               
               
                   
                 53.1 SiO2 
                  4.8 SiO2 
                   
                   
                   
                   
                 SiO2 
                 9 
                   
                 10 
               
               
                 KMAS(A) 
                 20.0 K2O 
                  1.5 K2O 
                 0.54 
                   
                 1590 
                 Amorphous 
                 K2O 
                 # 
                   
                 # 
                 0.63 
                 17 
                 19 
                 1 
                 10 
                 T 
               
               
                 No. 52 
                  9.0 Na2O 
                  1.0 Na2O 
                   
                 −6.3 
                 (Eut) 
                 (No peaks) 
                 Na2O 
                 # 
                 31 
                 # 
                 49 
               
               
                   
                 33.8 Al2O3 
                  2.3 Al2O3 
                   
                   
                   
                   
                 Al2O3 
                 14 
                   
                 32 
               
               
                   
                 39.9 SiO2 
                  4.6 SiO2 
                   
                   
                   
                   
                 SiO2 
                 17 
                   
                 17
A method for insulating an article requiring resistance against repeated exposure to temperatures exceeding 900° C. uses saline soluble, non-metallic, amorphous, inorganic oxide, refractory fibrous materials as thermal insulation. The compositions that can be used for that purpose include vitreous fibers based on SiO 2 , CaO, M g O, and optionally, A 2 O 3 .