CARBONATE OF LIME.
Dr. Clark, inventor of the soap-test, recommended a method of purifying water containing carbonate of lime, which has been successfully followed in many places, especially in England. It consists of adding caustic lime to water containing carbonate of lime. By this process, 28 grains of caustic lime result in the precipitation of 100 grains of lime carbonate. Or, to put it in a practical shape, where a tank contains 30,000 gallons of water, each gallon being impregnated with 30 grains of lime carbonate, 36 pounds of caustic lime will be sufficient to precipitate the whole of the impurity, making a total deposit of 164 pounds.