204 



The Artificial Production 



[April, 



tubular vessel, k, called the regenerator, through the tubes of which 

 hot water exhausted of ammonia flows in the opposite direction 

 from the boiler a. Here an interchange of temperature takes 

 place, the solution of ammonia becoming heated while the exhausted 

 liquor is cooled. The solution of ammonia, thus heated, then passes 

 on into the closed vessel above the boiler and containing the coil b, 

 where it is still further heated, while the gaseous ammonia and steam 

 within the coil b are partially cooled and condensed, and it then flows 

 by the pipe h into the boiler a, to serve for a repetition of the process. 

 The hot liquor exhausted of ammonia meanwhile flows from 

 the boiler in a regulated current through the pipe j into the tubes 

 of the regenerator k, thence through a cooling worm, m, surrounded 

 by water, where its temperature is sufiiciently reduceil, and then 

 passes into the absorber h, furnishing the supply of water for 

 dissolving the ammonia as already described. 



This machine has been largely used in the south of France for 

 eft'ecting the crystallization of salts by cooling, and several have 

 been sent out to India for making ice. 



In 1862 Mr. Kirk,* of the Bathgate Chemical Works, invented 

 a machine in which the alternate compression and expansion of air 



was applied as the means 

 of refrigeration, on the 

 same principle as Stirling's 

 air-engine for obtaining 

 motive power. This ma- 

 chine, which is represented 

 by Fig. 3, has been used 

 in paraffin oil works for 

 effecting the separation of 

 solid paraffin from the oil ; 

 it has also been worked at 

 Messrs. Flower's brewery 

 at Stratford-on-Avon, and 

 one has been sent to China 

 for making ice. The ar- 

 rangement of the machine 

 is very good ; but for 

 making ice it is expensive, 

 on account of the relatively 

 large expenditure of power 

 required. Messrs. Mort and 

 Nicolle,t of Sydney, in Aus- 

 tralia, have quite recently 

 patented another apparatus, in which the expansion of cold com- 

 pressed air is proposed to be applied ; but the principle on which it 



f^pccification, No. 1218. 



t Specification, No. 3278. 



