130 



Scientific Proceedings (92). 



(NaCl, CaCl 2 , etc.) causing an increase in the osmotic pressure, 

 viscosity, swelling, etc., while the salts with bivalent anion (sul- 

 fates, oxalates, etc.) do not cause such an increase. A very strik- 

 ing proof for the correctness of this statement is found in the fact 

 that the action of salts with monovalent cation and monovalent 

 anion (type NaCl) is equal to that of salts with monovalent cation 

 and bivalent anion (type Na 2 SO.i) when the molecular concen- 

 tration of the former is exactly twice the molecular concentration 

 of the latter; thus showing that only the cation influences the 

 gelatin, while the anion has apparently no effect. For gelatin 

 previously treated with an acid it was found that the salts with 

 monavalent anion and monovalent cation (type NaCl) bring about 

 the same effect as a solution of a salt with bivalent cation and 

 monovalent anion (type CaCU), when the molecular concentration 

 of the latter salt is exactly one half of that of the former salt, 

 showing that only the anion has any effect in this case. 



R. Lillie 1 had stated that the treatment of gelatin with neutral 

 salt causes a lowering of the osmotic pressure. This is not correct 

 and he was misled by the fact that he studied the osmotic pressure 

 of the solution in the presence of the salt, in which case the elec- 

 trolytic dissociation of the metal gelatinate formed under the 

 influence of the salt is repressed. As soon as the excess of salt is 

 washed away the increase of osmotic pressure of the gelatin solu- 

 tion due to the salt treatment shows itself, provided that the salt 

 used had a monovalent cation. When the cation is bivalent no 

 such increase is found. 



The writer is inclined to explain all these phenomena on the 

 assumption that neutral salts act upon proteins, which, like gelatin, 

 are stronger acids than bases, by forming metal proteinates. The 

 anion either does not enter into combination at all with the gelatin 

 or enters into a combination where its influence on the protein is 

 not felt. 



When gelatin had been previously treated with an acid, e. g., 

 hydrochloric acid, gelatin chloride or hydrochloride is formed, 

 which dissociates into a positive gelatin ion and a negative chlorion. 

 Neutral salts act upon such gelatin chloride by exchanging their 

 anion with the protein. 



1 Lillie, R. S., Am. J. Physiol, 1907, XX, 127. 



