I'M 



them on eartli. And where E. spenks in his paper of the kinetic 

 interpretation of the osmotic pressure, it seems to rae that he too 

 sliould worlv with snbstances as they exist on earth, and not with 

 such where Thermodynamics is ehminated. 



For throngh the elimination of the actions between the molecules 

 just the "according-to-probability unordered kinetic" element (the 

 kinetic equivalent of Thermodynamics), wliicli is brought about by 

 the mutual collisions has been done away wit!:, and oidy the 

 "roughly kinelic" element remains, which then, moreover, leads to 

 to the opposite result. 



In conclusion I can adduce no better evidence of tlie validity of 

 my considerations than tlie following. 



For a gas mi.vture (even if necessai-y of ideal gases) of e.g. 0, in 

 Nj — separated frou) pure N^ l\y a semi-permeable membrane, whicli 

 does not let through O^ — the osmotic pressure would just as for 

 li(piid mixtures, be represented by tlie above equation (1). Here 

 too tiie yas mixture would rise in an ascension tube (in consequence 

 of the diffusion tendency of the pure nitrogen) till the necessary 

 counler iin's-suri' iiad been reaclieil, which then prevented the further 

 .intrusion of llie nitrogen. Hut here too "liie osmotic pressure" starts 

 from the pure niliogen outside the iTiixiiire, and not from the 0, m 

 the mixture. Tliat ihere is here no question of a separate excess of 

 pressure of (lie ()„, appears from this that at the beginning of the 

 experiment the gas [)ressnres on tlie two sides of the membrane are 

 perfectly tlie same, (both = 1 atm.), the sum of the partial pressures 

 of the O2 -j- that of the N^ of course being precisely equal to the 

 pressure of the N, on tiie otiier side of the membrane. The excess 

 of pressure does not make its appearance until ri/Vrr the appearance 

 of the (lifftisioii — and arises, as lias been said, from the piu'e 

 nitrwjen. 



Tiiese observations, whicii in my opinion are conclusive for this 

 problem, have already been made and elaborated in my Lehrbnch 

 der Matiiematischen Chemie (1901), p. 30-31. 



4 May. 1915. 



