and in the Condensation of Vapours. 397 



care, and frequently repeated, and always with very uni- 

 form results ; and as the estimates which we have adopted, 

 with respect to the quantities of heat which are developed 

 in the combustion of hydrogen and in that of carbon, 

 have been confirmed so as to leave little doubt upon this 

 subject, upon investigating the cause of the great differ- 

 ence between the quantity of heat actually developed in 

 the combustion of the 85 parts of sulphuric ether burned 

 in the experiments which we have examined, and the 

 quantity given by calculation, we are compelled, in my 

 opinion, to admit that there is an error in the analysis 

 of this liquid, and that it does not contain so much free 

 and inflammable combustible matter as M. de Saussure 

 ascribes to it. 



As it seems to me to be much more probable that an 

 error has been committed in determining the quantity of 

 free hydrogen in this substance than in determining the 

 quantity of carbon, I shall suppose with M. de Saussure 

 that there is really in one pound of sulphuric ether (of the 

 specific gravity of 717) 0.59 of carbon ; but instead of 

 estimating the quantity of free hydrogen in this liquid 

 according to the results of M. de Saussure, I shall adopt 

 the estimate of Mr. Cruickshanks. 



This excellent chemist concluded, from his experi- 

 ments, that in the vapour of sulphuric ether the carbon 

 is to the hydrogen as 5 to i. 



In the 0.85 pound of sulphuric ether (specific gravity 

 717) which were mixed with the 0.15 pound of alcohol, 

 in order to form one pound of the mixed liquid employed 

 in my experiments, there were 0.5015 pound of carbon ; 

 and dividing this number by 5, we shall see that this 

 carbon ought to be united with 0.1003 P oun d of free 

 hydrogen, instead of being united with 0.1651 pound, as 

 we shall suppose according to M. de Saussure. 



