74 Examination of the received Doclrines 



Some philofophers tell us that the cavfe of this pheno- 

 menon of different bodies requiring different quantities oi ca- 

 loric to indicate the fame temperature (or, in other words, 

 the caufe of their having different capacities for heat) arifes 

 from the different degrees of affinity which different bodies 

 poflefs for heat ! Ts this an explanation ? — Different bodies 

 hol3 different quantities of heat, lecdufe they have different 

 capacities :— Different bodies hold different ouantities of heat, 

 hecauje they have different affinities ! — yet we are to confider 

 the one term as expreflive of a property, and the other as 

 expreffive of the cavfe of that property ! Is this confident 

 with that accuracy and precifion which fhould prevail in 

 the language of fcience ? 



But this is not all. Heat is confi;!ered as exiffing in two 

 diftinet (tales ; free, and in chemical union. When heat 

 is in equilibrio in any place; in other words, when a body 

 is in equilibrio with the bodies which furround it with re- 

 fpecl: to its heat [that is, has received heat from the common 

 flock proportioned to its capacity] ; that quantity which it 

 contains is termed latent heat ox caloric, com 1 ined caloric; 

 heat in chemical union. We are told that in this ftate it 

 is not perceptible by any external fign or organ of fenfe ; 

 that it does not affeet the thermometer, but remains qui- 

 efcent in thofe bodies of which it conftitutes a principle j 

 and that it is then, more or lefs, in a fiate of confinement. 



Is the heat in any body termed latent becaufe the body 

 has not a capacity to receive more? No; for if, by any 

 means, an addition be made to the common ftock of. a pre- 

 ferred fyffem of bodies, each individual fubftance will (till 

 provide lodging for a fliare of the added quantity, propor- 

 tioned to its- capacity, in relation to the capacity of the reft. 

 It fhould be obferved too, that, let the common temperature 

 be what it may, if heat be in equilibrio, the portion in 

 each body is, by fome at lead, held to be latent, in contra- 

 diftinclion to what they term free heat. Hence it follows, 

 that the quantity of latent heat in a given body differs in 

 different feafons of the year; for heat may be in equilibrio 

 in any fyltem of bodies in fummer as well as in winter. An 

 afTemblage of afferent bodies, in equilibrio as to caloric, in 



Jamaica^ 



