4i8 On the Determination of the [Dec. 



to a diminution in the capacity of the new compound for heat. 

 This hypothesis, which is merely an expansion of that by means 

 of which he explained the emission ar. :. absorption of heat during 

 the change of state of bodies, is liable to very strong objections, 

 which have prevented the greater number of philosophers from 

 adopting it • but which were not quite decisive, and therefore 

 insufficient to destroy the hypothesis entirely. It has still several 

 partizaus. Dr. Crawford adopted it, and it was some years ago 

 explained in detail by Dr. Irvine, jun. 



All the facts relative to the specific heat of bodies being 

 proper to throw light on this question, we shall examine in this 

 point of view some of those which result from our experiments. 



1. Oxide of azote (composed, according to Davy, of 0633 

 azote and 0-367 oxygen). 



Specific heat of, by calculation .... 0*2404 

 By our experiments 0*2369 



2. Carbonic acid (composed of carbonic oxide 0*634, and of 

 oxygen 0*366, Mem. d' Arcueil. ii. 253). 



Specific heat of, by calculation 0*2692 



By our experiments 0*2210 



3. Red oxide of lead (composed of Lead 0*9, oxygen 0*1, 

 Berzelius, Ann. de Chim. Ixxviii. 14). 



Its specific heat by calculation (thatl „ n , qn 



of lead being 0*0282) J 



Bvthe experiments of Lavoisier and"! „ ri/ . ori 

 ■, , r /■ U*Ub22 



Laplace J 



4. Red oxide of mercury (composed of 0*85 mercury, and 

 0*15 oxygen, Chenevix). 



Its specific heat by calculation (that") r\.r\c.c\c\ 



of mercury being 0*029) J 



By the experiments of Lavoisier and "\ n.™-, 



Laplace J 



5. Water (composed of 0\S7 oxygen, 0*13 hydrogen). 



Its specific heat by calculation 0*6335 



By experiment 1*0000 



If we now examine how far this difference between experi- 

 ment and calculation corresponds with the law of Dr. Irvine, we 

 shall find that, for the three compounds, 1, 2, 4, they enter into 

 the general law ; for though it has not been directly observed 

 that there is a disengagement of heat during the formation of 

 these bodies, the condensation, which the elements experience in 

 forming these combinations, proves tiiat such a disengagement 

 must have really taken place. This is not the case with the 

 third example, the red oxide of lead. We ought equally to 

 believe that heat has been disengaged during its formation; and 

 yet its specific heat is somewhat greater than the mean. It is 

 true, that as the difference is but small, and as it is derived from 



