ON THE HEAT DEVELOPED IN COMBUSTION. ]J7 



not afford more heat in its combustion than olive oil, when 

 burned in its natural state. The result of three experiments 

 showed me, that rape oil thus purified does in i'act yield 

 more heat than olive oil. The difference is indepd pretty 

 considerable, and more than I could have suspected. 

 The combust, of lib of purified rape oil gave 



93-073 of water heated 180*. 

 ■ olive oil gave 90*43p. 



Chemists may tell us, whether the quantity of incombus- 

 tible matter separated from rape oil in purifying it be suf- 

 ficient, or not, to account for this difference. 



On comparing the results of the experiments made with Comparison of 

 white wax and those with the purified oil, it appears, that 01 an wax * 

 equal weights of these substances afford nearly equal quan- 

 tities of heat in their combustion : and as in fact this ought 

 to be the case, from the quantities of combustible matter 

 they contain, the result tends to strengthen our confidence 

 in this method of measuring the heat developed in combus- 

 tion. 



It was with the combustion of 



lib of white wax <)4*682lbs of water heated 180°. 

 lib of purified oil g3*073lbs. 



As the object I had chiefly in view in this series of Combustion of 



experiments was to ascertain the quantities of heat de- nidr °g en and 

 1 . \ carbon the ob- 



veloped in the combustion ot pure hidrogen and carbon, ject of re- 

 in order to render this method useful in some chemical searcn » 

 analyses, I examined particularly those inflammable sub- 

 stances, that had been analysed with most care. 



Several attempts have been made to ascertain these „, . , 



. A •- , ,. . ... This has been 



interesting questions by direct experiments, in burning attempted 



puie hidrogen, or pure hidrogen and carbon; but the results direc t J y« 



of these researches have varied so much, that they cannot 



be relied on. 



According: to Crawford, the heat developed in the com- u - . 



( . Hidrogen rat- 



bustion of one pound of hidrogen gas is sufficient to ed higher by 



raise the temperature of 410lbs. of water 180° F. But the p a T wford . than 

 r , r . . , , b y Lavoisier : 



estimation of Mr. Lavoisier is much lower. According to 



him this heat would raise only 22lr>9 lbs of water the same 



On 



