J 13 ON THE HEAT DEVELOPED IN COMBUSTION. 



carbon the On the other hand Mr. Lavoisier estimates the quantity 



contrary. o ^ heat developed in the combustion of charcoal much 



Perhaps boMi higher than Dr. Crawford. I have many reasons to 

 rate this too believe, that they both estimate it too high: and, if this 



opinion be confirmed, we must estimate the h*at de- 



hidrogen too velopcd in the combustion of hidrogen a little higher even 



' than Crawford has done, to be able to account for that 



manifested in my experiments. 

 Charcoal 8c- From several experiments, which I made five years ago, 



cording to the it appeared to me, that one pound of charcoal, dried as 



much as possible before it was weighed by heating it red 



hot in a crucible, was not capable of raising mote than 



from 52 to 54 lbs. of water from the temperature of 



melting ice td a boiling heat. 

 Craw ford, and According to Crawford this heat should suffice to boil 

 Lavoisier. 57-606 lbs.; and according to Lavoisier, 72*375 lbs. 



We shall see how these estimates agree with the results 



of my experiments. 

 Results from As the experiments made with wax yielded very uniform 

 wax compared results, and as the analysis of this substance has been made 



with tliosecal- .,, Tin i .1 ,• • <» 



culatedfrom wltn g reat care » l &nal I examine how the quantities ot 

 its component hidrogen and carbon in this substance agree with the quan- 

 paits " tity of heat, that it afforded me in combustion. 



According to the analysis of Messrs. Gay-Lussac and 

 Thenard, a pound of this substance contain 



Carbon • ...0-8179 



Free hidrogen ••.•0-1191 



If we adopt the calculations of Dr. Crawford, both for 

 the heat furnished by the hidrogen, and that furnished by 

 the carbon, we shall have for the heat that shsuld be fur- 

 nished by the combustion 



lbs of water 

 according to Of 0*1191 lb. of hidrogen, after the ratio of 410 raised from 

 Crawford, jb^ f wa ter raised from 3-i" to 212 e by 32? to '212° 



burning 1 lb. of hidrogen • • • • 48 83 I 



Of 0*8179 lb of carbon, after the ratio of 57'6o6 

 lbs. of water raised from 32° to 212° by burn- 

 ing 1 lb. of carbon 47*116 



Total of the heat, that ought to be furnished 



by the quantity of combustible matter (hj- — — -— . 

 drogen and carbon) in 1 lb of white wax • • • • 95'947ibs 



Quantity 



