Ferric Chloride Hexahydrate: 1,000 Parts of 10 % Solution Evaporated to 483 (Ph. G. 1882)

Boil a ferric chloride solution of 10 per cent iron down to just under half its weight and it sets on standing to a yellow crystalline mass. 483 parts per 100 parts of iron is the weight of ferric chloride with six molecules of water (our calculation; the pharmacopoeia gives no formula). It draws water from moist air, so keep it closed. Source: Pharmacopoea Germanica, ed. II (1882), English ed. New York 1884, Ferrum sesquichloratum. Start from the 10 % iron solution of the German Pharmacopoeia blueprint; other solutions are a different strength. Picture: iron(III) chloride hexahydrate (Benjah-bmm27, public domain).