FIG. 294.—PERKINS’ ICE MACHINE, 1834.
Among later ice machines of this type the Pictet machine was a conspicuous example. This employed anhydrous sulphurous acid as the volatile agent, and is described in United States patent No. 187,413, February 13, 1877; French patent No. 109,003, of 1875.
FIG. 295.—THE PICTET ICE MACHINE.
In [Fig. 295] is represented a vertical longitudinal and also a vertical transverse section of a Pictet ice machine. A is a double acting suction and compression pump, D and E are two cylinders which are similarly constructed in the respect that they are both provided with flue pipes and heads for a double circulation of fluids, one fluid passing through the pipes while the other passes through the spaces between the pipes, much like the condenser of a steam engine. The cylinder D is the refrigerator where the volatile liquid is evaporated to produce cold, and the cylinder E is the condenser where the gasified vapor is cooled and condensed again to liquid form to be returned to the refrigerator. The action is as follows: The pump A by pipe B draws from the chamber in the refrigerator D containing the volatile liquid, causing it to evaporate and produce an intense degree of cold which is imparted to the liquid surrounding it and filling the tank. This liquid is either brine, or a mixture of glycerine and water, or a solution of chloride of magnesium, or other liquid which does not freeze at a temperature considerably below the freezing point of water. Now, this non-congealable liquid being below the freezing point, it will be seen that if cans H be filled with pure water, and are immersed in this intensely cold non-congealable liquid, the water in the cans will freeze. This is exactly what takes place, and this is how the ice is formed. As the volatile liquid is drawn out of the refrigerator D through pipe B by the pump A it is forced by the pump through pipe C and into the chamber of the condenser E. A current of cold water is kept flowing around the pipes in E, coming in through a pipe at one end and passing out through a pipe at the other end. The compressed and relatively hot gases are by the contact of this cold water along the sides of the pipes cooled and condensed into a liquid again, which passes up the small curved pipe F and is returned to the refrigerator D, to be again evaporated by the suction of the pump to continue the production of cold. In large plants the non-congealable liquid and cans of water to be frozen are (in order to get larger capacity) carried to a large floor tank in a removed situation.
One of the earliest methods of producing ice in a limited quantity was by evaporating water by a reduction of pressure and causing the vapor to be absorbed by sulphuric acid, which has a great affinity for the water vapor. Mr. Nairne, in 1777, was the first to discover the affinity that sulphuric acid had for water vapor, and in 1810 Leslie froze water by this means. In 1824 Vallance obtained British patents No. 4,884 and 5,001, operating on this principle, in which leaden balls were coated with sulphuric acid to increase the absorbing surfaces, and which apparatus was effective in freezing considerable quantities of ice.
The carafes frappees of the Parisian restaurant were decanters in which water was frozen by being immersed in tanks of sea water whose temperature was reduced below freezing by the vaporization of ether in a reservoir immersed in the sea water. Edmond Carré’s method of preparing carafes frappees involved the use of the sulphuric acid principle of absorption, and to that end the aqueous vapor was directly exhausted from the decanter by a pump, and the said vapor was absorbed by a large volume of sulphuric acid so rapidly as to freeze the water remaining in the decanter.