a chemical product which appears under the form of greenish or yellow-brown odorless crystals or granules with a saline taste, is soluble in water, and is used as a catalyst (especially for synthetic , an iron salt with a saline taste, usually obtained as greenish crystals of the heptahydrate, which are converted to the white monohydrate above 100°C: used in inks, tanning, water purification, and in, raud(II)hüdroksiidi ja väävelhappe sool