134 On the Determination of the [Aug. 



Article XI. 



Memoir on the Determination of the Specific Heat of the 

 different Gases. By MM. F. Delaroche, M.D. and J. E. 

 Berard.* 



The subject proposed by the Institute as a prize at the meet- 

 ing of the 7'h January, 1811 ; namely, the determination of 

 the specific heat of the gases ; ■ had previously attracted the 

 attention of different philosophers, some of whom have treated 

 of it in detail : yet so little progress has been made in the inves- 

 tigation, though the question proposed be sufficiently simple, 

 that we are almost as far from being able to answer it with 

 precision as we were before it became the subject of investiga- 

 tion. 



Crawford, as far as we know, is the first person who began the 

 investigation. He published the result of his researches in 1788. 

 At that time a great number of experiments had been made upon 

 the specific heat of bodies in general. MM. Lavoisier and de 

 Laplace had already published the result of their experiments on 

 that subject, aiid had given a description of their calorimeter of 

 ice : yet Dr. Crawford preferred the method of mixtures of 

 water, or other bodies whose specific heat was considered as 

 known. After many unsuccessful attempts, which it would be 

 too tedious to describe here, he thought that he succeeded by the 

 following method. He procured two copper vessels, very thin, 

 and of the same shape, size, and weight. He filled one of them 

 with the gas that he wished to examine, and made a vacuum in 

 the other. He then heated both in boiling water, and plunged 

 both suddenly into cylinders containing a small quantity of cold 

 water, but sufficient to cover them. He subtracted the heat 

 communicated to this water by the exhausted vessel from that 

 communicated by the vessel full of gas, and considered the 

 remainder as the effect produced by the gas, or as its specific 

 heat. He had taken great precautions to ensure the accuracy of 

 his results ; but it is quite evident, from the smallness of the 

 change, that ho confidence could be placed in them. The rise 

 in the temperature of the water never exceeded 0*4° Fahrenheit. 

 The following is the table of his results : — 



* Translated from the Annates de Chimie for January, 1813, vol. lxxxv. 

 p, 72. This memoir gained the prize proposed by the Institute, and deserves 

 particular intention. It overturns the theory of animal beat advanced by 

 Crawford, and Lavoisier's theory of combustion. 



