99 



iiiG. with the old method, has been reduced to some mG. only; 

 we must herewith remember tliat the vapour tension of alcoliol is 

 considerably greater than that of water. Theietbre the 6^'' series of 

 experiments was undertaken at 0°; according to our expectations the 

 results were better than at 2J.4°. 



The experiments communicated here have taken away every actual 

 ground of existence tVom the opinion expressed tirst l)y von Schroeder, 

 viz. that here was a conflict with the second law of thermodynamics; 

 the second law, as one might think, remains untouched. Of course 

 the phenomenon of several substances swelling more in liquids than 

 in vapours, remains; but we think this can be sufficiently ex{)laine(l 

 by assuming that the absorption in vapour occurs extremely slowly 

 in the end. We have also investigated if not totally swollen gelatine 

 and celloidin placed in vapour, would absorb more water in our 

 new apparatus, and would come to the real equilibrium. This 

 appeared not to be the case; e.g. with gelatine of the following 

 compositions: 1 gelatine to 26 parts of water (in weight); 1:24,2; 

 1:J8,8; 1:15,8; 1:6,5, (the "false vapourequilibrium" is about 

 1 : 0.7) no change of weight was found for five days ^). So it goes 

 without saying that the absorption takes place exceedingly slowly. 



This is most pi-obably connected with the fact that the vapour 

 tension of gelatine (and iiumerous other substances) is already very 

 near to that of pure water when (hey have only absorbed a rather 

 small quantity of water ^); consequently all the further water absorp- 

 tion of any importance is only of slight influence upon the vapour 

 tension. Or in other tei-ms, the difierence of the vapourtension of 

 pure water and of gelatine in "vapourequilibrium" is very small, 

 and consequently the absorption velocity will also be very small. 

 That it is yet very great in liquid water, may be easily explained 

 from the density which is 50000 times greater. 



We just wish to state that the determinations meant here have 

 all been obtained by the statical method, the deficiency of which 

 we have proved ; a true opinion can only be possible if the experiments 

 are taken along the dynamical waj ''), and if the real equilibrium 

 has been proved by placing the jellies alternately in vapour of 

 higher and lower tension. The values given for the composition of 

 the substances sw^ollen in the vapour of pure water are never true 



^) These experiments were also made in the dynamical meliiod vvilh U-lubes, 

 yielding the same result. 



^) Katz, tlicsp Pi'oc. 13, 05S (1910/11). 

 •) Or in the apparatus described ahuve. 



