Magnesium sulfate heptahydrate [MgSO4]
The most common hydrated form of magnesium sulfate (MgSO4·7H2O), Epsom salt, as colourless crystals.
Characteristics
- Contains seven water molecules, so it is less rich in magnesium than the anhydrous form.
- Very soluble: about 113 g per 100 mL of water at 20 °C.
- Source of magnesium, the central element of chlorophyll, and of sulfur.
- When heated it loses water, becoming kieserite and then anhydrous salt.
Role in the preparation: It dissolves easily in water to supply magnesium and sulfur to the preparation.
Caution: Classified as harmful if swallowed, in contact with skin or inhaled: wear gloves, keep it tightly closed in a dry place, and avoid excess that pollutes water.
Sources: Magnesium sulfate - Wikipedia
Documentary information: this is neither a recommendation for use nor a plant-protection or veterinary claim. Check your country's regulations before any use.