Ferric amido-sulphonate, Fe(SO₃.NH₂)₃

Ferric amido-sulphonate, Fe(SO₃.NH₂)₃, is prepared by dissolving ferric hydroxide and amido-sulphonic acid together in water. The solution obtained is bright brown in colour, and dries up into an opaque, amorphous, brittle mass, which is brown in colour, very soluble in water, but not at all deliquescent. It possesses the astringent taste of ferric salts of inorganic acids, and not that of the citrate or tartrate, the inference being that the iron constitutes the positive ion and is not included in the negative radicle.