76 
ME. CLEEK MAXWELL ON THE DYNAMICAL THEOEY OF OASES. 
of experiments on the diffusion of various gases out of a vessel through a tube into air. 
The coefficients of diffusion deduced from these experiments are — 
Air and Hydrogen *026216 
Air and Marsh-gas *010240 
Air and Ammonia *00962 
Air and Olefiant gas *00771 
Air and Carbonic acid .... *00682 
Air and Sulphurous acid . . . *00582 
Air and Chlorine *00486 
The value for carbonic acid is only one third of that deduced from the experiment 
with the vertical column. The inequality of composition of the mixed gas in different 
parts of the vessel is, however, neglected ; and the diameter of the tube at the middle 
part, where it was bent, was probably less than that given. 
Those experiments on diffusion which lasted ten hours, all give smaller values of D 
than those which lasted four hours, and this would also result from the mixture of the 
gases in the vessel being imperfect. 
Interdiffusion through a small hole. 
When two vessels containing different gases are connected by a small hole, the mixture 
of gases in each vessel will be nearly uniform except near the hole ; and the inequality 
of the pressure of each gas will extend to a distance from the hole depending on the 
diameter of the hole, and nearly proportional to that diameter. 
Hence in the equation 
e'^ + *= iA S'S (92) 
the term ^ will vary inversely as the diameter of the hole, while u x and u 2 will not 
vary considerably with the diameter. 
Hence when the hole is very small the right-hand side of the equation may be neg- 
lected, and the flow of either gas through the hole will be independent of the flow of the 
other gas, as the term JcAq^o{u. 2 — tq) becomes comparatively insignificant. 
One gas therefore will escape through a very fine hole into another nearly as fast as 
into a vacuum ; and if the pressures are equal on both sides, the volumes diffused will be 
as the square roots of the specific gravities inversely, which is the law of diffusion of 
gases established by Graham*. 
Variation of the invisible agitation ((3). 
By putting for Q in equation (75) 
q=|((«,+s, )’+(!', +» 1 ) ! +(® 1 +?,) ! +03-i)(s+»;+?;)), • • (93) 
* Trans. Loyal Society of Edinburgh, vol. xii. p. 222. 
