Bleaching Powder. Chlorine gas (slowly evolved from a mixture of 10 parts of common salt and 10 to 14 parts of binoxide of manganese, placed in an alembic of lead, and heated by steam, and with 12 to 14 parts of oil of vitriol previously diluted with a fourth of its weight of water, added) is conveyed into a chamber where sifted slaked lime is thinly spread on shelves. It is so cheaply made by the large manufacturers for bleaching purposes, that it is seldom prepared by druggists. The liquid chloride of lime may be made either by triturating the dry chloride with a little cold water till perfectly smooth, then adding more water, and filtering the solution: or by passing chlorine gas into a mixture of lime and water. The Beit. Pharm. directs a solution of 1.035 sp. gr. The Paris Codex directs 1 part of dry bleaching powder to be diffused in 45 of water. Soubeiran directs 1 part to 50; but prefers passing the gas from 1 part of binoxide of manganese and 4 of hydrochloric acid into a mixture of 1 part of lime and 50 of water. M. Opyl states that for the production of a good chloride of lime, the temperature of the chambers must be as low as possible. Winter is always found the most favourable season for its manufacture.