On the Thcunj of Mixed Gases. 409 



arc in the same r^tio with the weights of these 

 particles. The theorem then arises from the 

 consideration of weight, unconnected with 

 that relation, which the power of gravity, act* 

 ing upon the constituent particles, has to any 

 internal force, which actuates the elementary 

 parts of a body. On the other hand, the 

 centre of gravity being the place of motion and 

 inertia, it is the true centre of their effects, 

 namely, action and reaction ; finally, it is the 

 true seat of the mechanical energies of all 

 bodies, whether they be fixed, liquid or aeri- 

 form. These arc the reasons which induced me 

 a while ago to pronounce Mr. Dalton's manner 

 of proceeding rash ; because he will now per- 

 ceive, that his pncumatical maxim has no 

 power to injure those inferences, which it was 

 intended to destroy. My demonstration rests 

 on this principle : the aggregates of two sets of 

 heterogeneous particles, which are mutually 

 inelastic, form two elastic fluids ; the mecha- 

 nical energies of which reside in their respective 

 centres of gravity, ^fhe arguments constituting 

 the demonstration are given in my former 

 paper ; and I am ready to refer this part of the 

 controversy to the arbitration of the matliema- 

 tical world, should the Society honour that 

 paper with a place in their nlemoirs. 



The preceding remarks on Mr. Dalton's 



