Mr. J. C. Maxwell on the Dynamical Theory of Gases, 203 



ing on the diameter of the hole, and nearly proportional to that 

 diameter. 



Hence in the equation 



I ^ + %=^ A K-« 1 )+x / , 



dt dx 



(92) 



d Px 



the term -p will vary inversely as the diameter of the hole, 



while u t 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 neglected, and the flow of either gas through 

 the hole will be independent of the flow of the other gas, as the 

 term ^A/9 1 /o 2 (w 2 — u x ) 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 dif- 

 fusion of gases established by Graham*. 



Variation of the invisible agitation (/3). 

 By putting for Q in equation (75) 



+ (/9-l)(f 1 *+^+^)), . . J 

 and eliminating by means of equations (76) and (52), we fiud 



(93) 



3 



du< 



dv, 



dw. 



^AV+vf+VHp^+P^+ptf^ 



y (dv x dw\ y ^ (dw 1 du\ 





n 



(94) 



In this equation the first term represents the variation of invi- 

 * Transactions of the Royal Society of Edinburgh, vol. xii. p. 222. 



