EQUILIBRIUM OF HETEROGENEOUS SUBSTANCES. 165 

 B and G also denoting functions of the temperature. Therefore 



- (296) 



It will be seen (if we disregard the difference of notation) that this 

 equation is equivalent in form to (216), which was deduced from 

 a priori considerations as a probable relation between the quantity 

 and the potential of a small component. When a liquid absorbs 

 several gases at once, there will be several equations of the form of 

 (296), which will hold true simultaneously, and which we may regard 

 as equivalent to equations (217), (218). The quantities A and C in 

 (216), with the corresponding quantities in (217), (218), were regarded 

 as functions of the temperature and pressure, but since the potentials 

 in liquids are but little affected by the pressure, we might anticipate 

 that these quantities in the case of liquids might be regarded as 

 functions of the temperature alone. 



In regard to equations (216), (217), (218), we may now observe 

 that by (264) and (276) they are shown to hold true in ideal gases or 

 gas-mixtures, not only for components which form only a small part 

 of the whole gas-mixture, but without any such limitation, and not 

 only approximately but absolutely. It is noticeable that in this case 

 quantities A and C are functions of the temperature alone, and do 

 not even depend upon the nature of the gaseous mass, except upon 

 the particular component to which they relate. As all gaseous bodies 

 are generally supposed to approximate to the laws of ideal gases when 

 sufficiently rarefied, we may regard these equations as approximately 

 valid for gaseous bodies in general when the density is sufficiently 

 small. When the density of the gaseous mass is very great, but 

 the separate density of the component in question is small, the 

 equations will probably hold true, but the values of A and G may 

 not be entirely independent of the pressure, or of the composition 

 of the mass in respect to its principal components. These equations 

 will also apply, as we have just seen, to the potentials in liquid 

 bodies for components of which the density in the liquid is very 

 small, whenever these components exist also in the gaseous state, 

 and conform to the law of Henry. This seems to indicate that the 

 law expressed by these equations has a very general application. 



Considerations relating to the Increase of Entropy due to the 

 Mixture of Gases by Diffusion. 



From equations (278) we may easily calculate the increase of 

 entropy which takes place when two different gases are mixed by 

 diffusion, at a constant temperature and pressure. Let us suppose 



