REFRIGERATION. 341 



the thing signified, and calor, or the sensation 

 of heat which was produced in consequence of 

 the impression. The same observations equal- 

 ly apply to the different bodies by which the 

 sensation of cold is excited. 



Such is the mutable nature of the organs of 

 sense, whidi animated beings in general pos- 

 sess, that the sensations either of heat or of cold 

 which they feel, must ever be considered a test, 

 the most uncertain of the different degrees of 

 temperature existing in different bodies ; the 

 same quantity of matter of temperature, ap- 

 plied to the organs of sense, not only produces 

 different sensations to different individuals, but 

 to the same individual at different times. If a 

 man plunge his hand into a basin of water, at 

 the temperature of 50 of the present standard, 

 and remove it into water of the temperature of 

 100*, the former will feel cold, the other hot; and 

 if he remove the one of 50 to one of 33, the one of 

 50, which felt cold at first, will feel hot, when 

 compared to what it was when situated in that 

 of the temperature of 100. The most certain 

 means we possess of ascertaining the different 

 quantities of the matter of temperature existing 

 within a given bulk, consist in the different de- 

 gree of dilatation and of contraction, occasioned 

 to bodies exposed to the influence of that tem- 

 perature, under the different states of refrige- 

 ration and of combustion, as they may be called. 



