Guar gum is needed for producing sufficient viscosity. Because less is required, costs are reduced. This would help explain its presence in so many things today. In addition to guar gum's effects on viscosity, its high ability to flow, or "deform", gives it very favorable rheological properties. It forms breakable gels when cross-linked with boron. It is used in various multi-phase formulations for hydraulic fracturing, in some as an emulsifier because it helps to prevent oil droplets from coalescing, and in others as a stabilizer to help prevent solid particles from settling and/or separating. Fracking entails the pumping of sand-laden fluids into
Hydrochloric acid prepared by dissolving sal ammoniac in nitric acid, was described in the works of Pseudo-Geber, a 13th-century European alchemist. Other references suggest that the first mention of aqua regia is in Byzantine manuscripts dating to the end of the 13th century. Free hydrochloric acid was first formally described in the 16th century by Libavius, who prepared it by heating salt in clay crucibles. Other authors claim that pure hydrochloric acid was first discovered by the German Benedictine monk Basil Valentine in the 15th century, when he heated common salt and green vitriol, whereas others argue that there is no clear