444 
CHEMISTRY: J. WEB 
the electrolytes influence the rate of diffusion of water through a mem- 
brane it will simplify the presentation of my results if it is permitted to 
ascribe them to the attraction and repulsion of the charged particles 
of water by the ions. With this reservation we may say that the rise 
in the first part of the curve, in concentrations from 0 to about M/256, 
being caused by the prevalence of the attractive action of the anion 
upon the negatively charged particles of water, while the drop in the 
curve, when the concentration increases beyond M/256, is due to the 
fact that with a further increase in the concentration the repelling effect 
of the Na ion upon the water particles increases more rapidly than the 
attractive effect of the oxalate anion. With concentrations above M/16 
or M/8 the gas pressure effect of the solution commences to prevail 
over the electrostatic effects of the ions and the rate of diffusion of water 
rises again with increasing concentration. 
We may state incidentally that all these phenomena can be observed 
just as well in collodion membranes which have not been treated with 
gelatin, so that the gelatin plays no role in the action of the membrane 
on solutions of neutral or alkahne salts. 
4. This influence of the concentration of electrolytes upon the rate 
of diffusion of water explains the phenomenon of negative osmosis. 
It had been known for more than fifty years through the experiments of 
Dutrochet and Graham which were recently confirmed by Flusin,^ that 
solutions of certain acids, like tartaric and oxaHc, when separated from 
pure water by a membrane of pig's bladder produce a negative osmosis, 
i.e., water diffuses from the solution to the pure solvent. This is, of 
course, exactly the reverse of what one should expect on the basis of 
van't Hoff's theory. The writer has investigated this phenomenon and 
he found that it holds with certain exceptions for all the acids and all 
the alkalies, and that this expulsion of water from the solution (the so-called 
negative osmosis) occurs in exactly the same range of concentrations where 
the drop in the electrostatic attraction of sodium salts for water occurs, 
namely in concentrations from about M/256 to about M/8. Collodion 
flasks were filled with distilled water and submersed in beakers filled 
with solutions of acids or alkahes of different concentrations. The 
volume of water in the flask instead of diminishing increased when the 
concentration of the acid was between M/256 and M/16 or M/8 and the 
increase was the more considerable the higher the concentration of the 
acid or alkali within the limits mentioned. 
Our first rule states that in the presence of salts and alkalies with 
univalent and bivalent cation water diffuses through the collodion mem- 
