and in the Condensation of Vapours. 383 



between the results of our experiments made with olive 

 oil proves that one or other of our processes must have 

 been defective. 



The mean result of several experiments made with 

 olive oil gave me for the measure of the quantity of heat 

 developed in the combustion of one pound of this sub- 

 stance 90.439 pounds of water heated 180 F., or 120 

 pounds of ice melted, neglecting the fraction. 



In the experiments of M. Lavoisier, more than 148 

 pounds of ice were melted by the heat that appeared to 

 result from the combustion of one pound of this oil. 



It is true that this result was considered by that emi- 

 nent philosopher himself as too great to be capable of 

 explanation ; and he added, with that modesty which 

 rendered him so engaging and so respectable: "We 

 shall probably find ourselves under the necessity of 

 making corrections, perhaps pretty considerable ones, 

 in most of the results I have given ; but I did not 

 think this a sufficient reason to delay affording their 

 assistance to those who might intend to pursue the 

 same object." 



As it appears very probable that all the fat oils, when 

 perfectly pure, are composed of the same principles, I 

 was curious to see whether rape oil, purified by sulphuric 

 acid, would 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 puri- 

 fied, does, in fact, yield more heat than olive oil. The 

 difference is, indeed, pretty considerable, and more than 

 I could have suspected. 



The combustion of I Ib. of purified 



rape oil gave . . . 93.073 Ibs. of water heated 1 80. 

 I Ib. of olive oil gave . . 90.439 " " " " 



