On the Constitution of mixed Gases, 8c. 541 
diameters of the spheres of influence of each 
particle, are inversely as the cube root of the den- 
sity of the fluid. 
' The proposition applies to homogeneous elastic 
fluids only; how far it may apply to mixed fluids 
remains to be considered.—With regard to the 
constitution of such there may be several hypo- 
theses; some of which we shall now consider, 
1. The particles of one elastic fluid may repel 
those of another with the same force ce as they repel 
those of their own kind. 
In this case, if m measures of A were mixed 
with 7 measures of B, in the pneumatic appara- 
tus, and under the atmospheric. pressure of 30 
inches of mercury, the two would occupy m-+i 
measures of space. If they were of the same 
specific gravity, they would remain in the situ- 
ation they were left, of intimate mixture or of 
separation, as ithappened. If they were of dif- 
ferent specific gravities, the lightest would rise 
to the top of the vessel :—The pressure on each 
particle of the mixture would be equal to g0 
inches of mercury. 
Now with regard to the application of these 
principles; as we know of no two elastic fluids,’ 
which when mixed, obey the laws of their spe- 
