air. The ice chamber should also be lined with zinc, and be placed at the top or back of the chest, a waste pipe being provided for draining away the water, which may be stored in another zinc receptacle under the chest, and used as an ice bath for bottles of liquors, etc. Ice quickly melts if surrounded by water or air, therefore keep the ice chest closed and well drained. If you have a piece of ice but no proper receptacle for it, you may keep it for a long time even in summer if you wrap it in a blanket and place it in a dark, dry place. Unless you are quite sure of the purity of ice, never mix it with food or beverages; cool down to the required temperature by surrounding the vessels in which the food or beverage is contained with a mixture of pounded ice and salt. An ice closet, or refrigerator, should not be kept in a kitchen; place it in the larder, at all events well away from the direct sunlight; choose the darkest corner. The interior should be kept scrupulously clean.
Filters.—Absolutely pure water is not to be found in nature, for even rain (natural distillation, resulting from condensation following on evaporation of sea, lake, river and soil surface water by the sun-rays) absorbs gases and dust as it descends through the various atmospheric strata. Lake, river and spring waters contain gases, earthy salts and organic matter. The salts are not to be feared unless present in large quantities, but the presence of organic matter, if not always dangerous, should give rise to suspicion. Organic matter in water is usually the result of decomposition, and whether of vegetable or animal origin is nearly always unwholesome; but too often such organic matter may comprise chemical poisons or the so-called poison secreting specific, or pathogenic, microbes. To get rid of superfluous earthy salts (more especially lime and magnesia) and organic matter, various methods of purification are adopted. Water supplied to towns by companies or municipalities is usually filtered through extensive and deep beds of sand gravel and other materials. Sometimes the water is first run into tanks, chemicals added, and the superabundant lime allowed to deposit before the water is run on the filters. Domestic filters are constructed on much the same principle, the water being made to pass through layers of sand, charcoal, spongy iron, porous earthenware or patent compositions. Charcoal and iron are believed to have a chemical as well as a mechanical influence, as they absorb oxygen and part with it, and also absorb deleterious gases. The varieties and styles of filters differ so widely that it is almost impossible to give prices. A domestic filter may be made by thoroughly charring the inside of an oaken cask (this is best done by burning spirits of wine in it), then placing curved porous tiles at the bottom, covering this with a layer of carefully cleansed gravel, upon the top of which should be a finer gravel, and finally sand or coarsely ground charcoal. The danger of all filters is that they soon get foul if constantly used, and then water passed through them is only contaminated. There are
