See also Filters.

If an emulsion of clay is poured into a soap solution, the clay gradually separates out without clarifying the liquid. When a few drops of hydrochloric acid, however, are added to a soap solution and a small quantity—about 1.5 per cent—of a clay emulsion poured in, the liquid clarifies at once, with formation of a plentiful sediment. Exactly the same process takes place when the waste waters from the combing process in spinning are treated with clay. The waters which remain turbid for several days contain 500 to 800 grams of fatty substances per cubic meter. If to 1 liter of this liquid 1 gram of clay is added, with 15 to 20 per cent of water, the liquid clarifies with separation of a sediment and assumes a golden-brown color. Besides the fatty substances, this deposit also contains a certain quantity of nitrogenous bodies. Dried at (100°C.) 212° F., it weighs about 1.6 grams and contains 30 per cent of fat. The grease obtained from it is clear, of good quality, and deliquesces at 95° F. After removal of this fat, the mass still contains 1.19 per cent of nitrogen.

Sterilization of Water with Lime Chloride

In order to disinfect and sterilize 1,000 parts of drinking -water, 0.15 parts of dry chloride of lime are sufficient. The lime is stirred with a little water into a thin paste and introduced, with stirring, into the water to be disinfected and a few drops of officinal hydrochloric acid are added. After 1/2 hour the clarification and disinfection is accomplished, whereupon 0.3 parts of calcium sulphite are added, in order to kill the unpleasant smell and taste of the chlorine.

Clarifying Muddy Water

The water supply from rivers is so muddy at times that it will not go through the filter. When this happens agitate each barrel of water with 2 pounds of phosphate of lime and allow it to settle. This will take but a few minutes, and it will be found that most of the impurities have been carried down to the bottom. The water can then be drawn off carefully and filtered.

Removal of Iron from Drinking Water

The simplest method for removing the taste of iron in spring water is to pass the water through a filter containing a layer of tricalcic phosphate either in connection with other filtering materials or alone. The phosphate is first recovered in a gelatinous form, then dried and powdered.

For Hardness

A solution perfectly adapted to this purpose, and one which may be kept a long time, is prepared as follows:

Thirty-five parts of almond oil are mixed with 50 parts of glycerine of 1.26 specific gravity and 8.5 parts of 50 per cent soda lye, and boiled to saponification. To this mixture, when it has cooled to from 85° to 90° C. (185° to 194° F.), are added 100 to 125 parts of boiling water. After cooling again, 500 parts of water are added, and the solution is poured into a quart flask, with 94 per cent alcohol to make up a quart. After standing 2 months it is filtered. Twenty hydrolimeter degrees of this solution make, with 40 parts of a solution of 0.55 grams of barium chloride in 1 quart of water, a dense lather 1 centimeter high.