and in the Condensation of Vapours. 387 



According to the calculations of M. Lavoisier, we have, 



For 0.7721 Ib. of carbon . 55.881 Ibs. of water heated 180. 

 " 0.1208 Ib. of hydrogen . 26.780 " " " " 



Total ... . 82.661 " " 



According to the calculations of Dr. Crawford, it is, 



For 0.7721 Ib. of carbon . 44-478 Ibs. of water heated 180. 

 " 0.1208 Ib. of hydrogen . 49-528 " " " " 



Total .... 94.006 " " " " 



According to the experiments, I pound of purified rape 

 oil furnished heat sufficient to raise 93.073 pounds of 

 water 180; and i pound of olive oil enough to heat 

 90.439 pounds. 



From all these comparisons it follows that the estima- 

 tions of Dr. Crawford agree much better than those of 

 M. Lavoisier with the results of my experiments. 



SECTION III. Experiments made with Spirit of Wine, 

 Alcohol, and Sulphuric Ether. 



As the component parts of these inflammable liquids 

 may be considered as well ascertained by the results of 

 the excellent investigation of M. de Saussure, I under- 

 took to examine them for the second time, in order to 

 discover what quantities of heat are developed in their 

 combustion. I had begun this undertaking five years 

 ago ; but, after having made a considerable number of 

 experiments, I desisted from it on account of the great 

 difficulties that occurred. As soon, however, as I had 

 found means of rendering my apparatus more perfect, I 

 formed the project of recommencing it. 



Before I enter into the particulars of my experiments, 

 I must say a few words respecting the difficulties that 



