JACQUES LOEB 



413 



which the swelling is depressed by the same amount is about half as 

 great for Na2S04 as for NaCl (for molecular concentrations from 

 m/256 to m/32), proving that the Na ion is responsible for the depres- 

 sion, while it is about eight times as high for NaCl as for CaCU. 

 The pH of the gelatin was practically the same in all solutions. 



All these data confirm our valency rule, whereby ions of the same 

 valency and the same sign of charge have, in the same concentration, 

 the same depressing effect on osmotic pressure, swelling, solubility in 



nJlUlLHiiilWri M M M 

 ^ 8192 4096 20481024 512 256 128 64 32 16 8 



Concentration 



Fig. 13. The depressing effect of neutral salts on the swelling of Na gelatinate 

 of pH about 9.3 is due to the cation of the salt, the depressing effect of NaCl being 

 half as great as that of Na2S04 of equal molecular concentration of Na2S04 while 

 that of CaCl2 is considerably greater owing to the fact that Ca is bivalent. 



alcohol, and viscosity of proteins; while the depressing effect increases 

 rapidly with the valency. The Hofmeister ion series are due to the 

 neglect of measuring the influence of the salts on the hydrogen ion 

 concentration of the gelatin solutions. This neglect has given rise to 

 the statement that salts, like sodium acetate, have the same depress- 

 ing effect on the physical properties of proteins as the sulfates. A 

 number of attempts to apply colloid chemistry to biology, pathology, 

 and medicine are based on such errors. 



