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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



order to cool a quantity of heated air or water 

 down to a moderate temperature, a large supply 

 of water is the best medium, not only on account 

 of its abundance and cheapness, but because of 

 its great capacity for heat. 



When any elastic fluid is compressed, it be- 

 comes hot, and if it then be cooled down to its 

 original temperature and be expanded, it is ren- 

 dered as many degrees colder by its rarefaction 

 as it was heated by its condensation; hence we 

 have here a means of producing low temperatures. 

 On the one hand we can ignite tinder by the heat 

 evolved in the compression of air in a glass cylin- 

 der ; and by the exhaustion of air in a bell jar the 

 temperature may be reduced so that the moisture 

 it contains is deposited as a mist. By the ex- 

 tremely rapid expansion of a liquefied gas when 

 pressure is removed, or of a volatile liquid when 

 its evaporation is hastened by mechanical means, 

 we obtain the most effective cooling powers. 

 The familiar experiment of freezing water or mer- 

 cury in a red-hot dish is effected by the enormous 

 expansion of liquefied sulphurous acid or of solidi- 

 fied carbonic acid, which substances regain the 

 heat they lost when undergoing the change of 

 liquefaction or solidification. 



The production of intense cold by the rapid 

 evaporation of ether projected in the form of a 

 fine spray is a process which has been introduced 

 with success into surgery by Dr. Richardson, for 

 the purpose of producing a local insensibility to 

 the pain caused by a knife or other instrument. 



By inclosing ether in an air-tight vessel, and 

 drawing off the vapor as fast as it is generated, 

 evaporation is greatly accelerated, while the ether 

 may be condensed again for further use. The 

 original apparatus of Harrison, which depended 

 upon this principle, consisted of a multitubular 

 boiler immersed in an uncongealable liquid such 

 as brine ; an exhaust-pump carried off the ether- 

 vapor which is rapidly formed at the expense of 

 the warmth of the salt-water. The reduction of 

 temperature may reach 24° Fahr., or what is 

 commonly called 8° of frost. The ether was con- 

 deused by passing through a worm-tube sur- 

 rounded by a stream of cold water, and the 

 chilled brine was made to circulate round metallic 

 vessels containing the water to be converted into 

 ice. 



Many improvements have been made on this 

 ether-machine, and one of the most complete 

 methods of working is now in operation on a 

 large scale on the premises of the Manchester 

 Patent Ice Company. 



Messrs. Sidely and Mackay, of Liverpool, are 



the patentees of the apparatus, the chief charac- 

 teristics of which are its adaptability to the satis- 

 fying of large demands, its economical use of the 

 cooling power of the ether-vapor, and its capabil- 

 ity of making ice in thick blocks. Not only are 

 exhaust-pumps used for evaporating the ether in 

 the refrigerator, but pressure is exerted to liquefy 

 the ether in the condenser. Both refrigerator 

 and condenser are tubular vessels. Now, as the 

 vapor passes from the refrigerator to be con- 

 densed by the pump, it is made to part with some 

 of its chilliness either to ether going to the re- 

 frigerator, or to water about to be frozen ; and 

 again in its return-passage to the refrigerator it 

 is deprived of any oil which it may have acquired 

 from the machinery. The whole of the cooling 

 apparatus is below-ground, and contained for the 

 most part in pits of cement or asphalt. The 

 water to be frozen is run into metallic tanks, be- 

 tween the inner and outer surfaces of which 

 chilled brine at a temperature of 15° Fahr., or 

 1*7° below freezing-point, is made to circulate, 

 the metallic vessels being connected by stout vul- 

 canized India-rubber tubing. The water during 

 freezing is kept in constant agitation, with two 

 objects — first, to remove air, and so obtain clear 

 ice ; and, second, to equalize the temperature 

 throughout, so as to prevent the water freezing 

 on the surface, as it ordinarily does on a pond. 

 The ice is formed first round the sides of the cell, 

 and gradually thickens till it closes up in the 

 centre. The clearness of the ice is greatly in- 

 creased by slow freezing, and to obtain this de- 

 sirable condition the time allowed is from sixty to 

 ninety hours. Each block of ice measures three 

 and a half feet broad by four feet long, and is 

 thirteen inches in thickness ; the weight varies 

 from six to seven hundred-weight. A simple con- 

 trivance to facilitate the removal of the ice by a 

 crane traveling on rails laid on beams overhead, 

 is a loop of rope which is frozen into each block. 

 The ease with which, when placed on the ground, 

 these large blocks can be slid about by the men 

 is very advantageous. In order to loosen the ice 

 from the cells, brine at any temperature above 

 32° Fahr. is made to circulate in place of the 

 frigorific liquid, and so greatly are the metallic 

 vessels cooled that it requires a period of about 

 an hour to loosen one of the blocks. 



The magnitude of the operations is such that 

 the engines can be worked up to one-hundred- 

 horse power, and are capable of turning out thirty 

 tons of ice per day. On the occasion of a recent 

 visit to this interesting factory there were one 

 hundred and eighty tons of ice in store, and some 



