22 THE POPULAR SCIENCE MONTHLY. 



tank, between the rows of cans, run the coils of pipe through 

 which the ammonia passes. The evaporation of the ammonia 

 constantly going on within this system of pipes cools the brine 

 down to 15 or 18 Fahr. In order to equalize the temperature in 

 all parts of the tank the brine is kept in constant circulation by 

 a revolving agitator, which resembles a propeller-screw. Sur- 

 rounded by this frigid liquid the water in the cans becomes con- 

 gealed to uniform hard blocks of ice, weighing about three hun- 

 dred and twenty pounds each. A tank of the dimensions above 

 given contains five hundred cans. About sixty hours are required 

 for the freezing process. 



In Fig. 1 the tank, with its flooring, is shown in the middle of 

 the building. To the right of this is the pump, and at the ex- 

 treme right is the boiler-room. Over the tank is a traveling 

 crane, by which the cans containing the ice are lifted out and 

 conveyed to one end of the room. The crane consists of a beam, 

 with a pair of wheels under each end, which travel on tracks six 

 or seven feet above the floor. By means of the tackle hung from 

 this beam a man raises a can of ice above the floor, and then 

 pushes the crane with its load to the end of the room. Here the 

 can is put into a sort of swinging box and tilted over into a slant- 

 ing position, mouth downward. Tepid water is then allowed to 

 run over the can from a line of small jets on each side. In two or 

 three minutes the block of ice is melted free from the can and 

 slides through a shute into the ice-house. The box is an auto- 

 matic contrivance, and, as soon as the ice has left it, it reverses, 

 turning the can upright and shutting off the water. In some fac- 

 tories the can is dipped into a tank of warm water to loosen the 

 ice. In the figure, a can is seen suspended from the crane ; at the 

 back, under the middle window, is the small tank of warm water 

 for dipping the cans ; and in front of the next window two blocks 

 of ice are lying. The room at the left is the ice-house. It has 

 double walls packed with non-conducting material, and is shown 

 with two layers of blocks in it. 



The ammonia gas, after passing through the coils of pipe in 

 the freezing tank, is drawn through a pipe into the great pump, 

 where by the return stroke of the piston it is compressed and 

 forced out through another pipe into the condenser. In Fig. 2 

 the condenser is shown in an upper room. It consists of several 

 coils of pipe, over which cold water is kept running. The small 

 pipes which run down obliquely from the ends of the coils are 

 to carry away the ammonia as it becomes liquefied into the stor- 

 age tank, which is the horizontal cylinder on the floor with the 

 condenser. From the storage tank the ammonia, still under 

 pressure, passes down into one of the large vertical cylinders 

 shown in the lower part of the figure, and from this it goes into 



