re/peeling Heat or Caloric. 143 



mining how much its length is diminifhed or its diameter 

 fricreafed. 



Some may fav, that the cafe of the converfion of water into 

 fleam is not held by them as one of thofe that prove the 

 pafhng of heat from a fenfible to a latent (late, and that 

 therefore our reafoning, drawn from that example, will not 

 invalidate the doctrine; "• for in the cafe of water they con- 

 fider the heat as in fimple mixture, and it would be an abufe 

 of words to call fo weak an union by the name of combina- 

 tion." 



I reply, that this cafe was one of the earlieft brought in 

 fupport of the doctrine, and alfo thought to be one of the 

 ftrongefl: ; and if the good underftanding of any has led them 

 to give it up, it is the more furprifing they fhould be fo blind 

 as to continue upholding a fabric which was built on this as 

 one of its foundation ftones; and which does not appear to 

 me to be upheld by any one fa& that may not be as fatif- 

 fa&orily explained, without admitting the exifience of heat 

 in two diftincl ftates. 



But, fay thefe, two different fluids of the fame temperature 

 when united will often give out heat — What can weMay of 

 this heat, but that it was latent or combined in one or both 

 of the fluids, and that it is thrown out as fenfible or free 

 heat-by their union? I would fay no fuch thing without a 

 previous examination of all the accompanying phaenomena; 

 and one of thefe I find to be a reduction in the volume of the 

 compound, which is lefs than that of the fumof the two. The 

 moleculae of the two fubftances occupy lefs room united than 

 in their refpeelive fluids. For inftance, when fulphuric acid 

 and water are joined, the volume of the mixture is lefs than 

 that of the two before mixture ; there is, therefore, lefs lodg- 

 ing-room left for the heat: in other words, the capacity of 

 the compound for heat is lefs than the fum of the capacities 

 of the ingredients : therefore, compared with furrounding 

 bodies, it lias now too large a quantity, and, by the law of 

 equilibrium, muft give cfF the furplus to the furrounding 

 bodies in proportion to their capacities, reftrving of fuch 

 furplus onl) that portion due to itfelf, and neceflary to give 

 it fuch an increafed temperature as the furrounding bodies 

 K % will 



