On the T/ieo7y of Mixed Gases, 299 



consequently the equilibrium in question can- 

 not take place unless the necessary disposition 

 of the heterogeneous particles be first esta- 

 blished; so that the former requisite of the 

 theory is entirely depended on the latter. — 

 After having acquired a distinct idea of a fluid 

 mixture, composed of gases possessing separate 

 equilibria, we cqme in the next place to in- 

 vestigate the mechanical properties of such a 

 compound; in the prosecution of which en- 

 quiry, the comparative densities of the con- 

 stituent fluids must be first determined in a 

 horizontal plane, the situation of which is 

 given in the common space. 



Let the figure PMINKV represent this 

 space, in which M VNK is the given plane. — 

 Now since every point of this plane may be 

 supposed to be at an equal distance from the 

 earth's centre, the density of every homoge- 

 neous gas supported by it, will be the same 

 in all parts of it. Let the constituent fluids be 

 denominated A and B ;. also let C denote the 

 compound ; moreover let the densities of A and 

 B, at P, be p and q ; let PX and X Y be two 

 equal evanescent parts of the line PV. Now 

 seeing the pressure acting upon an elastic fluid 

 is as the density of it, the fluxionary incre- 

 ments of p and qy are as these quantities ; but 

 the densities of A and B, in the point X, are 

 pp 2 



