Magnesium sulfate heptahydrate (formula MgSO4 · 7H2O), also known as sulfur bitter, bitter salt, diarrhea Lee salt, Epsom salt, white or colorless needles or oblique columnar crystals, odorless, and bitter cold, molecular weight: 246.47, specific gravity 1.68, soluble in water, slightly soluble in ethanol and glycerol, soluble own crystal water at 67.5 ℃. Thermal decomposition, 70﹑80 ℃ lost four molecules of water of crystallization. About 200 ℃ lose all crystal water into anhydrous. In the air (dry) is easily weathering powder, gradually removing crystal water when heated becomes anhydrous magnesium sulfate, the product does not contain any toxic impurities. Magnesium sulfate heptahydrate dissolved because it is not easy, easier than anhydrous magnesium weighed facilitate quantitative control carried out in the industry. Mainly used for fertilizer tanning ﹑ ﹑ ﹑ plastic pigment dyeing catalyst ﹑ ﹑ ﹑ porcelain manufacture paper ﹑ ﹑ matches and fire materials. Can be used for dyeing cotton ﹑ thin wire, as a weighting agent and filler products kapok cotton yarn; Epsom salts used as medicine. [1-2] Chinese name English name of magnesium sulfate heptahydrate magnesium sulfate heptahydrate aka sulfur bitter; bitter salt; epsomite; Epsom salts formula MgSO4 · 7H2O Molecular Weight 246.47 CAS Registry Number 10034-99-8 EINECS Accession No. 231-298- 2 Melting point 1124 ℃ water soluble H2O: 1 M at 20 ° C, clear, colorless appearance of white powder density 1.68 danger symbol Xi