1819.] 



of the Theory of Heat. 



193 



To make the law intelligible, which we propose to make known, 

 we have joined, in the preceding table, to the specific heats of 

 the different bodies, the relative weights of their atoms. These 

 weights are deduced, as is known, from the ratios observed be- 

 tween the weights of the elementary substances that unite 

 together. The care taken for some years in the determination 

 of the proportions of most chemical compounds can only leave 

 slight uncertainties with respect to the data which we have 

 employed ; but as no precise method exists of discovering the 

 real number of atoms of each kind which enter into a combina- 

 tion, it is obvious that there must always be something arbitrary 

 in the choice of the specific weight of the elementary molecules ; 

 but the uncertainty can be only in the choice of two or three 

 numbers which have the most simple relation to each other. 

 The reasons which have directed us in our choice will be suffi- 

 ciently explained by what follows. We shall satisfy ourselves 

 at present with saying, that there is none of the numbers on 

 which we have fixed which does not agree with the best esta- 

 blished chemical analogies. 



We may now, in consequence of the data contained in the 

 preceding table, calculate easily the ratio which exists between 

 the capacity of atoms of a different kind. We may remark, that 

 in order to pass from the specific heats furnished by the obser- 

 vations to those of the particles themselves, it is sufficient to 

 divide the former by the number of particles contained in the 

 same weight of the substances which we compare ; but it is 

 clear that the number of particles for equal weights of matter are 

 reciprocally proportional to the density of the atoms. We shall 

 obtain, therefore, the result wanted by multiplying each of the 



Vol.. XIV. N°ill. N 



