446 
CHEMISTRY: J. WEB 
permeable for solutions of crystalloids are impemeable for solutions of 
colloidal salts, e.g., the salts of gelatin. It can be shown that the 
permanent osmotic pressure of solutions of gelatin salts is influenced by 
the electrostatic action of ions in a similar way as is the rate of diffusion 
of water. I have found that water diffuses into neutral solutions of Na, K, 
Ca or Ba gelatinate as if the particles of water were positively charged. 
Since Ca and Ba (and all the other bivalent cations) have a greater 
repelKng effect on positively charged particles of water than Li, Na, K 
or NH4, the initial rate of diffusion of water should be greater when 
gelatin (in a 1% solution) is in combination with a monovalent cation 
than when it is in combination with a bivalent cation. I have tested 
this idea and found it confirmed. When we separate 1% gelatin solu- 
tions from distilled water by a collodion membrane the initial rate of 
diffusion of water into the solution is a Httle over twice as great when the 
gelatin exists in the form of sodium gelatinate than when it exists as cal- 
cium gelatinate, both having the same hydrogen ion concentration. 
The permanent osmotic pressures of the two types of solutions show also 
approximately the same ratio, being about or a little over twice as 
great in the case of sodium gelatinate as in the case of calcium gelatinate 
of the same concentration of gelatin as well as of hydrogen ions. Li, K, 
and NH4 gelatinate behave like sodium gelatinate while Mg, Sr, and Ba 
gelatinate behave like calcium gelatinate. 
Water particles behave like negatively charged particles in the presence 
of gelatin salts in which the gelatin is a cation, e.g., gelatin chloride or 
gelatin sulfate. If 1% solutions of these two gelatin salts of the same 
hydrogen ion concentration are prepared and put into collodion bags, 
water diffuses twice as rapidly into the gelatin chloride solution as intQ 
the gelatin sulfate solution. The osmotic pressures of the two solutions 
vary also as about 1:2 or a little less.^ 
The full report of the experiments on the influence of the concentra- 
tion of electrolytes on the electrification and rate of diffusion of water 
through membranes will appear in the Journal of General Physiology. 
iGirard, P., Paris, C. R. Acad. Set., 146, 1908, (927); 148, 1909, (1047-1186); 150, 1910, 
(1446); 153, 1911, (401); La pression osmotique et le mechanisme de Tosmose, Publications 
de la Societe de Chimie-physique, Paris, 1912. 
? Bartell, F. E., /. Amer. Chem. Soc, 36, 1914, (646). Bartell, F. E., and Hocker, C. D., 
Ibid,, 38, 1916, (1029-1036). 
' Bernptein, J., Elektrobiologie, 1912. 
* Perrin, J., /. Chem. Physique, 2, 1904, (601); 3, 1905, (50). 
6 Loeb, J., /. Gen. Physiol., 1, 1918-19, (717). 
^Flusin, G., Ann. chim. phys., 13, 1908, (480). 
' Loeb, J., /. Gen. Physiol., 2, 1919, No. 1. 
