Mole (unit) measure the amount of substance (although in practice it is usual). There are many physical relationships between amount of substance and other physical quantities, the most notable one being the ideal gas law (where the relationship was first demonstrated in 1857). The term "mole" was first used in a textbook describing these colligative properties. Chemical engineers use the unit extensively, and decimal multiples may be more suitable for industrial use. For convenience in avoiding conversions in the imperial (or American customary units), some engineers adopted the "pound-mole" (notation "lb-mol" or "lbmol"), which is defined as the number of entities in
Dobson unit Dobson unit should eventually be replaced by an appropriate SI unit and that the unit mmol m-2 was the most convenient and least cumbersome option. It expressed the hope that this unit would eventually supplant the Dobson Unit. However, as of March 2017, there is little evidence that this has occurred; for example the Dobson unit is still used by NASA and by the World Ozone and Ultraviolet Radiation Data Center in their reporting of total ozone amount. NASA uses a baseline value of 220 DU for ozone. This was chosen as the starting point for observations of the Antarctic