Note:  Do not rely on this information. It is very old.

Bleaching Powder

Bleaching Powder is prepared by the action of chlorine on slaked lime. The lime should be free from iron or manganese, which are frequent impurities, and is slaked with water, great care being needed, as too much or too little is detrimental to the final product. It is then spread in thin layers over the floor of the "chambers," which are made of lead or stone. The chlorine is then passed over, the supply being regulated so as to keep the temperature below 60°.