30 THEORIES OF HEAT. 



Crawford fays, .7936. Even of equal bulks that of iron is 

 lefs than that of water, as I fee in the fame table. I can only 

 fuppofe that Dr. Thompfon has flumblcd on the fpecific gravi- 

 ties infiead of fpecific heats, and lliere he would have been 

 right enough. 

 The fime expe- I will fay only a few words farther on the queflion, whether 

 terminesYpedfic ^o'^'C^ contain caloric in proportion to their fpecific heats or 

 heats is alfo the not. Now firfl; of ail when they continue of the fame capa- 

 cities.^ ' The''^" •^'^'^*- Suppofe the capacity of a body to be to that of water 

 abfolute heats as ] to 5, i. e. double. The fame quantity of heat that raifes 

 ate (bytnference ^ater two degrees, raifes it one; 2° more raife the body one 

 extended thro' , r r , , , /• 



the whole range Hiore, and lo on as tar as we can go upwards, and the reverie 



from zero) downwards in the fcale. Kut fuppofe another body whofe 

 the fame ratio. <-'apacity is to that of water as 20 to 5, i. e. quadruple. Each 

 \^ of the heat in water raife this new body one degree up- 

 wards, and the reverfe downwards, as far as we know. Now 

 is it not probable here that the whole heats are in proportion 

 to the capacities thus determined, fince like thermometrical 

 portions of heat taken out of each and applied to wafer afre6t 

 it in that ratio ? Tlie fpecific heats of bodies are faid to be 

 different, when the fame quantity of heat raifes one a different 

 number of degrees from the other, and that regularly as far as 

 we can examine. Therefore each degree in each contains a 

 quantity of heat proportional to its capaciiy. But the whole 

 heat is made up of degrees, therefore the whole heats are 

 proportional if the capacities remain the fame. Dr. Thomp- 

 fon grants this to he abfolute fadl to the extent of our experi- 

 ments. 

 If the capach'ics But if the capacity be fuppofed to vary, firft let it diminifli. 

 jhould-vary y[ ^| qiiantitv of heat given out is the diHerence of the 

 ratine changes, whoIe heats of the two different ftates of the body; and the 

 the only confe- whole heat of it in each ftate is proportional to its capacity, 

 That heat -would and the whole heat of its higheft capacity is equal to that of 

 i>e given out or [[^ jovvefl plus the heat given out. Tlierefore the change of 

 ^cJmmon tlmpera- Capacity has made no alteration on the whole heat of the body 

 rKr^we;er^or<;</, computed from a higher point, but will turn out the fame as 

 :"/2;V/;;. if no change had taken pUce. 



nvcu/d bepicpor- If the capacity be fuppofed to increafe, a fimilar reafoning 

 tionedtothenew ^^^^^^ q^^^ jj^^^ the heat ftiU may be computed in the fame 



.tapaciti' *. , 



way. Such are a few arguments on tbe other fide of the quef- 



tioB 



