The artificial production of cold has engaged attention from remote ages. The application of spontaneous evaporation in Eastern countries was the earliest method employed to produce ice.
America has the honor of being the home of the inventors who first achieved success in making artificial ice by modern methods. Jacob Perkins, in 1834, and Professor Twinning, of New Haven, Conn., in 1850, each procured British patents. The former did not procure a patent in this country, but Professor Twinning secured one in 1853. Two years later, he had a machine in operation at Cleveland, Ohio, which produced 1,600 pounds of ice in twenty-four hours’ run. This was a favorable result from a pioneer machine of an estimated capacity of 2,000 pounds in this time.
Much credit is due these early inventors, who introduced a type of machine which is now extensively employed, and is known as the compression system.
In 1851, Dr. John Gorrie, of New Orleans, La., patented a machine for producing ice, by compressing and expanding atmospheric air. This machine was also the pioneer of its class. It gave rise to what are known as air machines, used in England and on the Continent, and extensively employed for facilitating the transportation of fresh beef and mutton on the ocean.
In 1848, Ferdinand Carré, of France, contrived an original process for employing aqua ammonia. In 1865 he patented an ice machine, and at the French International Exposition, in 1867, daily produced six tons of ice. This has proved to be a notable invention, the present absorption system being based upon it and extensively used.
Efforts have been directed to expediting the spontaneous evaporation of water; a reduction of pressure being effected by a vacuum pump, and the vapors removed by a suitable absorbing medium. The utilization of cold obtained by the evaporation of other liquids, more volatile than water, have received attention.
There have been discovered a number of freezing mixtures, some of which produce wonderfully low temperatures. The addition of salt to broken ice is the best known of these; it is commonly employed in making ice creams and ices, and is of great commercial importance as applied to refrigerator cars and cold storage houses.
Of all these methods the compression, absorption and air machines, and the freezing mixture of ice and salt, have entered into commercial uses in this country. The details of the latter method are referred to in Chapter VI. Regarding the others, some account of the principal operations involved, and of the natural phenomena upon which they are based, will be given.
Principles of Ice Machines.—It has been observed of gases, that by compressing them to a fraction of their original volume, heat was produced. If the compression was great, most gases were liquified by it. A few gases were found which would not liquify, and were designated as permanent. By relieving the pressure, gases will resume their original bulk, and the heat of compression is gathered up or reabsorbed by them.
There is, naturally, a constant tendency toward the preservation of an equilibrium of temperature among the atoms of any body, and also between different bodies. This exchange is carried on upon a grand scale, in the economy of nature. Where the difference in degree is small the exchange is effected slowly, but where it is great the initial transfers proceed rapidly and with vigor.