PHYSICS-NINETEENTH CEN/T HEAT/.l f 531 



very remarkable experiments by Professor Andrews havfe'^hown, toc^/ 

 that matter may exist in a condition intermediate J>ejween the"' gaseous 

 and the liquid states, and that, in fact, there is .a ofyttinuity ifi jits 

 passage from the one to the other. ) / > 



The absorption of heat attending the vaporization of liquids has 

 in recent times been practically applied in the production of artificial 

 cold. Thus the apparatus of M. Carre, which is merely a simple but 

 very efficient air-pump, quickly produces iced water by means of the 

 cold attending the evaporation of the liquid itself in a vacuum. The 



FIG. 245. 



same inventor has applied Faraday's plan of condensing gases to the 

 obtaining of a liquid that on resuming the gaseous state rapidly absorbs 

 heat. The apparatus is represented in Figs. 245 and 246. A is a 

 strong wrought iron vessel partly filled with a concentrated solution 

 of ammonia, and connected by the tube G with an annular space sur- 

 rounding the vessel D, and the whole is hermetically closed. At the 

 beginning of the operation all the liquid is contained in A, which is 

 gradually heated as shown in Fig. 245, while D is plunged in a cistern 

 of cold water E. The ammonia then condenses into a liquid in D, 

 and when A is cooled as in Fig. 246, the pressure which caused its 

 condensation being thus removed, it rapidly returns to the gaseous 

 state and is absorbed by the water in A. This change of state is ac- 



