ON MIXED GASES. 7 



known theorem in mechanics ; for the same reason, r into the Examlnationof 

 fluxion of w is equal to the product of d, y, x and fluxion x; Mr. Dalton's 

 hence R into fluxion of W is to r into fluxion oiw, as D istQ d'^ '''/^^ef ^"'*^ 

 but D is to d, as fluxion W is to fluxion w ; therefore R and r 

 are equal: consequently the centres of gravity of A and B 

 coincide, and the point of (heir coincidence is also the centre 

 ofthesytemC. Thus it appears, that when the component 

 gases of a fluid mixture possess separate equllbria, their densi- 

 ties are every where in a given ratio ; and they have a com- 

 mon centre of gravity ; the converse of which is equally true, 

 viz. if their densities be not everywhere in a given ratio, 

 and if they have not a common centre of gravity, they do not 

 possess separate equilibria. 



It is necessary to observe, in this stage ©f the inquiry, that 

 though we admit the particles of A and B to be inelastic in 

 relation to each other, the concession must be strictly confined to 

 tJie particles themselves ; for the gases which are composed of 

 them are elastic bodies : they therefore receive and communi- 

 cate motion according to the laws which are peculiar to bodies 

 of this description. The foregoing properties of a fluid mix- 

 ture, which has been supposed to be duly adjusted, is now to 

 be used in the examination of the fundamental proposition of 

 the new theory intended to explain the constitution of the 

 atmosphere. According to this proposition, if two gases come 

 into contact, the particles of which are perfectly inelastic in 

 respect of each other, the particles of A meeting with no re- 

 pulsion from those of B, further than that repulsion, which, as 

 obstacles in the way they may exert, would instantly recede 

 from each other as far as possible in their circumstances, and 

 consequently arrange themselves just as in a void space. The 

 precedingare the words of the author of the Theory; and it is 

 readily granted that the particles of such a heterogeneous mix- 

 ture would recede from each other as far as circumstances will 

 permit; the present subject of inquiry then brings the dispute 

 to this issue — can that arrangement take place amongst the 

 particles of two or more gases, which will make their centres 

 of gravity coincide in one point ? For the separate equilibria 

 of the fluids, which enter into the constitution of the com- 

 pound, will not be established until this arrangement be per- 

 fectly formed. The completion of this process being essential 

 tQ the pew theory, the effect of it has been, perhaps, toa 



