Note 407 — ARTIFICIAL ICE. COOLING LIQUORS.

History of Cold, title i. 17; title v. 3; title xv. 7. [The method of making one or two freezing or cooling mixtures will not perhaps be without interest here. Where snow is not at hand, a mixture of 5 parts of powdered nitre and 5 of powdered sal-ammoniac may be mixed with 16 parts of water. This reduces the thermometer from +50° to about +10° F., or, 9 parts of phosphate of soda, 6 of nitrate of ammonia, and 4 of dilute nitric acid, reduce the thermometer from +50° to -21°; 5 parts of common salt, 5 of nitrate of ammonia and 12 of snow, reduce it from the ordinary temperature to -28°. The most intense degree of cold, probably known, has been produced by Dr. Faraday in his experiments upon the liquefaction of gases. This was effected by placing solid carbonic acid mixed with æther, under the air-pump, and exhausting.]