120 .Examine; ion of the received Doclrinfs 



■its original bulk, then the added heat is latent ; it is in che- 

 mical union ; it is combined caloric ! Becaufe now not cog- 

 nisable by our ferifes? No. We fee the volume of the 

 iieam much larger th4n that of the water; and the more 

 heat we add, the greater is the incrcafe of volume while 

 water is left to receive it. Yet I am not to believe that the 

 hear is cognifable by any organ of fenfe or external figh 1 

 In other word?, 1 am commanded to believe as true, a ftate- 

 ment which the evidence of my own fenfes makes it impof- 

 iible I can give credit to. 



But, fay the advocates for this doclrine, a fubfianee fo 

 charged with caloric as to become vapour, will not indicate, 

 by the thermometer, any further increafe of temperature, 

 though we continue to pour heat into the liquid that pro- 

 duces the vapour; therefore the extra heat nmft have become 

 latent in the fteam that has been generated. Nay, we can 

 prove the fact; for this fame latent heat may again be made 

 j'gnjible in the common procefs of condenfation. 



This mode of reafoning appears to me to be more fpecious 

 than juft. It is demanding that the common thermometer 

 mould do in this cafe what it never does in any. This in- 

 ftrument never tells the quantity of heat patting into' any 

 body, even in thofe cafes where heat is counted fenjible or 

 free; it onlv tills the comparative quantity palling into itfelf 

 from the body in which it is immerfetl, or with which it is 

 in contact:, to bring it into equilibrium with that body as to 

 heat. 



Boiling water, fleam, the materials of which the thermo- 

 meteY is made, become each charged with heat in proportion 

 fo their capacities, and this whether the thermometer be in 

 the water or in the fteam. The thermometer kept in the 

 fleam w*U never rife higher than 212°, " becaufe there the 

 heat is latent!" Keep it in boiling water for a year, and it 

 will not rife higher than 21 2 ; yet there the heat is fenjible ! 

 Is this diftinclion reconcilable with common fenfe ? But the 

 rcfuli may even be altered at pleafurc. It will not rife higher 

 than 212 in boiling water under the common atmofphere :-— ' 

 in other words, if we wilh to raife the heat higher, we muft 

 put a greater preffura upon the Water. Confine" the water (o 



« th.a 



