187 



also diffuse, but this diffusion is now arrested by the semi-permeable 

 memltrane, so that the diffusion is only brought about by the water. 



Thesis VIII. Apart from what actually takes place on or in the 

 semi-permeable membrane — hence when simply an imaginary mem- 

 brane is taken, which does allow one sort of molecules to pass 

 through, but not the other kind — it is easy to determine ,the just 

 mentioned nuuibers of diffusing molecules according to Boi.tzmann's 

 method (in agreement with the kinetic interpietation of the thermo- 

 dynamic potential). (See among others .Sechs Voi'trage p. 20 — 21). 

 Then the required lot/arif/unic ineiuber arises of its own accord. 



Thesis IX. If there is interddion between the two kinds of 

 molecules, another term r,;;' simply arises hi/ the side oï — /o</(l — x). 

 If however a = 0, as is (lie case for so-called ideal solutions (this 

 is also the "imaginary" case to which E. alludes in his Remarks) 

 all the above remarks conti)iue to be valid unimpaired — which is in 

 contradiction with E.'s view in his Remarks. The diffusion, the 

 intrusion of the water till the required excess of pressure has been 

 reached — everything remains the same. 



E.'s opinion that the rise of the water in the osmometer can only 

 lake place through the three factors named by him, of which the 

 interaction of the two kinds of molecules is one, must therefore be 

 rejected with the greatest decision. 



To what absurdities this conception would lead appears from this 

 that when as dissolved substance a substance is taken with a very 

 high critical temperature, and wlien this substance yet forms an 

 "ideal" solution with water, loitlwut interaction (« = 0), as is the 

 case with many organic substances (also sugar), the partial vapour 

 pressui'e of that dissolved substance (e. g. sugar) is vanishingly small 

 with respect to that of watei'. So there does not take place any 

 "evaporation" at all. According to E. the vapour pressure of the 

 sugar would become equal to tiie osmotic pressure — which for a 

 normal solution amounts to no less than 24 atmospheres! In reality 

 the partial pressure of the dissolved sugar will perhaps amount to 

 a billionth m.m. in the imaginary case mentioned by E. (sugar is 

 about in that case). 



Thesis X. It appears in my 0|)inion sufficiently from the above 

 that the kinetic interpretation of the osmotic pressure — which is 

 always reappearing tigain in new forms — is moving and has moved 

 in a wrong direction, and should again be founded on the simple 



