Calcium Chloride, Purified: Iron Oxidised with Chlorine Water and Thrown Down with Milk of Lime

Pure calcium chloride, as Thorpe's Dictionary (1912) gives it: chalk in hydrochloric acid, then chlorine water to oxidise any iron, milk of lime to throw the iron down, filter, acidify the slightly alkaline filtrate with hydrochloric acid, and evaporate to the crystallising point. Chlorine is a poison gas: fume hood. The picture: our diagram.