Magnesium sulfate heptahydrate (molecular formula mgso4.7h20), also known as thiobitter, bitter salt, laxative salt, is white or colorless needle or inclined column crystal, odorless, cool and slightly bitter, easily soluble in water, slightly soluble in ethanol or glycerin. This product does not contain any toxic substances.

It is mainly used in the manufacture of fertilizer, leather, printing and dyeing, catalyst, papermaking, plastics, porcelain,pigment, match, explosive and fireproof materials. It can be used for printing and dyeing of thin cotton and silk, as the weighting agent of cotton silk and the filler of kapok products; it can be used as laxative salt in medicine.