THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



FEBRUARY 1842. 



XIII. On Mixed Gases. By James Ivory, K.H., M.A., Hofi. 

 M.R.I. A. i Instil. Reg. Sc. Paris, et Reg. Soc. Gotting. Cor- 

 resp.^ 



THE subject of mixed gases is of great importance in 

 many physical researches ; and, in particular, the atmo- 

 sphere being a mixture of gases, the inquiry into its constitu- 

 tion essentially depends upon the knowledge of the laws ac- 

 cording to which elastic fluids combine in the same volume. 

 But although the subject has been often discussed, it is still 

 embarrassed by several difficulties which it is very desirable 

 to clear up. 



Suppose a gas contained in an envelop, the pressure, den- 

 sity, and volume being p, p, u, and the temperature 6 : con- 

 ceive that the envelop is extended on all sides, the enlarged 

 volume being V ; in consequence the gas will expand, and 

 after a little time all motion will cease, and the elastic fluid 

 will assume a state of rest and equilibrium, exerting the same 

 pressure at every point of the envelop. Now, when the vo- 

 lume of the gas was u, the pressure was j) ; wherefore when 

 the volume is enlarged to V, the pressure will be lessened to 



p. :^, which is the exact measure of the elastic force of the 



expanded fluid, and the pressure at every point of the enve- 

 lop. 



Let us now take a different gas, which has no chemical 

 action on the other, the pressure and density being 7/, 0', 

 the temperature 6 as before, and the volume u' = V— u, 

 so that the sum of the two volumes u and u' is equal to the 

 volume of the envelop. If this new gas be introduced into 



* Communicated by the Author. 

 Phil. Mag. S. 3. Vol. 20. No. 1 29. Feb. 1842. G 



