Refrigerator (Lat. refrigere, to make cool), an apparatus by which various articles, generally meats and drinks, are kept cool or are reduced in temperature. The ordinary food refrigerator is usually in the form of a chest which has a compartment for ice and one or more compartments for the food. Most of the older forms of refrigerators did not completely separate the ice from the food compartment, and many of them were merely chests with double sides separated by some non-conducting substance, as charcoal, in which the ice as well as the articles to be kept cool were placed on shelves indiscriminately. In either case the moisture from the evaporating ice filled the whole apparatus, and caused the contents t6 begin decaying soon after their removal, and indeed prevented their being preserved long while they were within it. In the presence of moisture, particularly when it contains the effluvia from various meats and articles of food, decomposition will go on even at a temperature considerably below the freezing point, and this cannot be secured by the presence of ice. In a dry atmosphere, like that of the Andes or the California coast, meats may be preserved without ice.

If a current of air is made to circulate in a chamber surrounding an ice box, much of the moisture of the air will be condensed upon the box, and there will also be a constant collection of impurities contained in the air. To make such a refrigerator efficient, the air must be first dried by passing it through a vessel containing chloride of calcium or some substance which will rapidly absorb moisture. In either case the caloric absorbed by the ice to cool a continuous current causes it to melt rapidly. An efficient method is to place a tight ice box within a tight meat box, or surround the latter with an ice chamber, the meats to be first cooled in the open air.