cordially granted by Messrs. Sperry & Barnes, who furnished every assistance within their facilities to aid in making a thorough practical test. The results of this test constitute the basis of the present paper, Fig. 198 showing the detailed observations for a period of seven days of twenty-four hours. The averages of the various measurements are shown in Table I. A study of the brine temperatures in Fig. 198 will show that the period of the test embraced the entire range of temperatures to which the machine was subject, the brine reaching the same minimum and maximum twice during the seven days.

The results which measure the practical or commercial value of the machine are:

1st. That the total refrigerating effect of the machine during twenty-four hours was equivalent to the cooling of the circulating brine, an amount equal to the heat which would melt 40.67 tons of ice to water at 32° Fahr., or freeze 40.67 tons of water at 32° Fahr. into ice. This work is what is to be understood as "40.67 tons of ice-melting capacity."

The data and calculations affording this result are as follows:

2d. That if each pound of fuel consumed at the boilers evaporated 10 lbs. of water into steam at 45 lbs. pressure above the atmosphere, then each pound of fuel consumed in operating the refrigerating machine produced an amount of refrigerating effect equivalent to the heat which would melt 17.1 pounds of ice to water at 32° Fahr., or freeze 17.1 pounds of water at 32° F. into ice. The data and calculations giving this result are as follows:

DESCRIPTION OF MACHINE AND ARRANGEMENT OF APPARATUS.

Ammonia gas is distilled from a solution of about 28% anhydrous ammonia in water in the vessel A, Fig. 199, by means of the heat supplied by a steam coil taking its steam from the boiler B. This gas passes upward to C through a series of plates, which cause the

gas to take a tortuous passage, and thereby, in conjunction with the drip-pipes, induce any entrained steam or water to separate from the gas, so that the latter may pass into the condensing coil D, free from all influence due to the presence of water.

The coil D is immersed in water drawn from an artesian well, E, which maintains it at an average temperature of about 68° Fahr., so that the ammonia gas, which is under a pressure of about 150 pounds, must liquefy and accumulate in the bottom of the coil D, or in the reservoir F. From this reservoir it flows into a vessel H at a constant rate, regulated by the degree of opening of the valve G. The vessel H is maintained at a pressure of about 2 lbs. above the atmosphere through the suction of a pump I, which withdraws gas from H by steps presently to be described. The liquid ammonia relieved of pressure by entering H falls in temperature from about 68° to about 5° Fahr. through the fact that in the expansion of the liquid from the 150 lbs. pressure to the 24 lbs. pressure, a small fraction volatilizes, and the heat to supply the work, necessary to cause the volatilization, is abstracted from the liquid ammonia itself, thereby causing the temperature of the latter to fall.*

Through the coil shown in H, brine is circulated, which on entering is at about 22° Fahr. The refrigerated ammonia coming into contact with the brine coils, heat flows rapidly from the brine into the ammonia; and as the latter is maintained under the constant pressure of 24 lbs., for which pressure its boiling point is 5° Fahr., the heat thus taken from the brine causes the liquid ammonia to be entirely changed into vapor of ammonia at 24 lbs. pressure. The brine is thereby reduced in temperature from 24° to about 16° Fahr. The brine is pumped through the rooms or buildings to be refrigerated by the pipe J, J, J. The ammonia gas passes into the vessel K, which is maintained by the pump suction at a pressure of about one-half pound per square inch.

*The lowest limit of temperature here given is not to be understood as the lowest possible limit with this type of machine. A pressure of about ten pounds above the atmosphere may be maintained in H, and thereby the lowest temperature of the ammonia made about minus 12° Fahr. Such a pressure is adopted in a machine of the type under notice in use at the Gansevoort Cold Storage Warehouse, New York city, where observations by the writer have shown that the lowest temperature of brine averages less than zero Fahrenheit; which would require that the lowest temperature of the ammonia should be about minus 12° Fahr. allowing 11° difference between the inside temperature of brine coils and the animonia on the outside of the coils.