Colloidal Iron

Colloidal iron, together with a small quantity of ferrous hydroxide and a ferrous salt, is obtained by electrolysing a solution of pure gelatin and a dilute solution of an alkali chloride or sulphate between iron electrodes. The sol resembles those of lead and bismuth in that it bears a positive charge. The majority of metallic sols, on the other hand, are negative.

Colloidal solutions of iron in ether have been obtained by allowing sparks to pass between iron wire clippings immersed in that liquid and connected up with an induction coil.