597 



formed into black radiation as well when tlierc is a "black grain" 

 in the contracting reflecting enclosure, as in the absence of such a 

 "cataljser". Else we should get into collision with the second law 

 of thermodjmamics. ^) If there are N raonatomic molecules in a 

 vessel witli rough walls, distributed according to Maxwell's law, 

 and if this ideal gas is compressed by an infinitely slow shifting 

 of the walls of the vessel, the distribution finallv follows again 

 Maxwell's law, both when the molecules during the compression 

 can collide, and Avhen they could peneti-ate perfectly through each 

 other. Probably more examples might be found in which through 

 an "adiabatic influencing" of the separate degrees of freedom a 

 state of equilibrium arises from a state of equilibrium. '^) But in 

 general this is not the case, e.g. for molecules consisting of more 

 than one atom or for mon-atomic molecules on which an external 

 field of force acts. ') 



Chemistry. — "Equillbna in ternary .systems. XI." By Prof. 



F. A. H. SCHRPÏÏNEMAKERS. 



In all our previous communications we have always contemplated 

 the case that the occurring solid substances are ternary compounds. 

 Now we shall assume that a binary compound occurs. 



It is evident that we may deduce the saturationcurves under their 

 own vapour-pressure and the boilingpointcurves of a binary compound 

 in the same way as has been done in the previous communications 

 for a ternary compound. 



We take a compound composed of B and C, we represent this 

 in fig. 1 by the point F on the side BC of the components-triangle 

 ABC. We now take a definite temperature 7' and a pressure F in 

 such a way, that no vapour can be formed and the isotherm consists 

 only of the saturationcurve of F. This is represented in fig. 1 by 

 curve pq. 



On decrease of F, a gasregion occurs somewhere and also the 

 region L — G, which separates gas- and liquidregion from each other. 



1) M. Planck, Wanntestrahking II. Aufl. § 71. 



-) The two mentioned cases have this in common that the pressure only depends 

 on the total energy of the system, and not on its distribution over the different 

 degrees of freedom, 



'^) In an analogous way we can see that a canonical ensemble of gases 

 generally does nut remain canonical after an "adiabatic influencing". 



