Magnesium sulfate heptahydrate (molecular formula MgSO4 · 7H2O), also known as sulfur bitter, bitter salt, diarrhea salt, diarrhea salt, is white or colorless needle-like or oblique columnar crystal, odorless, cool and slightly bitter, molecular weight: 246.47 The specific gravity is 1.68, easily soluble in water, slightly soluble in ethanol and glycerin, and soluble in its own crystal water at 67.5 ° C. Thermal decomposition, 70, 80 ℃ is lost four molecules of crystal water. At about 200 ° C, all water of crystallization was lost to anhydrate. It is easily weathered into a powder in the air (dry), and the crystal water is gradually removed during heating to become anhydrous magnesium sulfate. This product does not contain any toxic impurities. Because magnesium sulfate heptahydrate is not easy to dissolve, it is easier to weigh than anhydrous magnesium sulfate, which is convenient for quantitative control in the industry.
Mainly used in the manufacture of fertilizers, tanning, printing and dyeing, catalysts, paper making, plastics, porcelain, pigments, matches, explosives and fire-resistant materials. It can be used for printing and dyeing thin cotton cloth and silk, as a weighting agent for cotton silk and as a filler for kapok products; it is used as Epsom salt in medicine.