A white soluble compound, MgSO4, existing as the anhydrous compound (rhombic; r.d. 2.66; decomposes at 1124°C) and in hydrated crystalline forms. The monohydrate MgSO4.H2O (monoclinic; r.d. 2.45) occurs naturally as the mineral kieserite. The commonest hydrate is the heptahydrate, MgSO4.7H2O (rhombic; r.d. 1.68), which is called Epsom salt(s), and occurs naturally as the mineral epsomite. This is a white powder with a bitter saline taste, which loses 6H2O at 150°C and 7H2O at 200°C. It is used in sizing and fireproofing cotton and silk, in tanning leather, and in the manufacture of fertilizers, explosives, and matches. In medicine, it is used as a laxative. It is also used in veterinary medicine for treatment of local inflammations and infected wounds.
Subjects: Chemistry — Clinical Pharmacology and Therapeutics.