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Hyposulphite of Lime

Slack 5 ounces lime with enough water to make 4 pints, boil up with 10 ounces of flowers of sulphur, and pass into the solution sulphurous acid gas (free from carbonic acid) until it has become colorless. Then filter and evaporate to crystallization, at a temperature not exceeding 140° Fahrenheit. Another way to prepare this salt is to mix 44 ounces (by weight) of a solution of fused chloride of calcium of 1.238 specific gravity, with a warm solution of 25 ounces hyposulphite of soda in 30 ounces water; evaporate to 38 ounces, and pour off, while warm, from the crystals of chloride of sodium; then allow to crystallize, and purify the crystals by re-solution.