Epsom salt, sulfur bitter, bitter salt, epsomite; over MgSO4 the formula; m.p. 1124 deg.] C; density 2.66 g / mL 
magnesium sulfate, or anhydrous magnesium sulfate, the magnesium is a compound of anhydrous magnesium sulfate is a A commonly used chemical reagent and desiccant, but magnesium sulfate often refers to magnesium sulfate heptahydrate, which is a white fine or oblique columnar crystal, odorless and bitter. 
Chemical properties: white or colorless needle-like or oblique columnar crystal, odorless, cool and slightly bitter, molecular weight: 246.47, specific gravity 1.68, soluble in water, slightly soluble in ethanol and glycerin, soluble in 67.5 °C Crystal water. Decomposed by heat, 70, 80 °C is the loss of four molecules of crystal water. At 200 °C, all crystal water is lost to an anhydrate. It is easily weathered into powder in air (dry), and gradually removes crystal water into anhydrous magnesium sulfate when heated. This product does not contain any toxic impurities. Magnesium sulfate heptahydrate is easier to weigh than anhydrous magnesium sulfate because it is not easily dissolved, which facilitates quantitative control in the industry. 
Magnesium sulfate often refers to magnesium sulfate heptahydrate (because it is not easy to dissolve, it is easier to weigh than anhydrous magnesium sulfate, which is convenient for quantitative control in industry.) There are also water, dihydrate, trihydrate and pentahydrate. Anhydrous magnesium sulfate. 
Magnesium sulfate heptahydrate has industrial grade and feed grade, granular, according to the size of 0.1-1mm, 1-3mm, 2-4mm three. 
Others such as anhydrous, monohydrate, dihydrate, and magnesium sulfate trihydrate are in powder form.