Chemicals may be employed for refrigerating purposes, but the really effective ones give a much lower temperature than freezing, and they are therefore not nearly so good as ice for the purpose. Equal parts of water, nitrate of ammonia, and carbonate of soda will yield a temperature about 35 below zero F. The cost of chemicals as refrigerators is, however, a great drawback to their use. After using them a solution is obtained which must be either evaporated to recover the salts or thrown away.