JACQUES LOEB 695 



a is unknown, and we therefore can only calculate for the present 

 the values of 



2y -\- z — 2x 



If we express the theoretical osmotic pressure of a grammolecular 

 solution in terms of mm. pressure of a column of HoO we get (with 

 correction for a temperature of 24°C.) 



297 

 22.4 X 760 X 13.6 X ^- = 2.5 X lO"* 

 273 



In other words, a theoretical pressure of 2.5 mm. H2O corresponds 

 to a concentration of 10"^ N. In the following tables all concentra- 

 tions are expressed in terms of 10~^ n and hence we only need to 

 multiply the values for 2^; + s — 2:^; given in our tables by 2.5 to 

 obtain the calculated osmotic pressure of the gelatin solution (neglect- 

 ing the osmotic pressure of the gelatin ions and molecules). 



Equation (1) holds in the case of solutions of all gelatin-acid salts 

 with monovalent anion; i.e. gelatin chloride, acetate, phosphate, 

 tartrate, citrate, etc. When, however, the anion of a gelatin-acid 

 salt is divalent, as in the case of gelatin sulfate, the equilibrium 

 equation becomes one of the third degree. If x be the hydrogen ion 

 concentration of the outside solution, the concentration of the SO4 



oc 

 ion in the outside solution becomes -. If y be the concentration 



2 



of the H ions of the free sulfuric acid in the inside solution, - is the 



2 



concentration of the SO4 ions of the free acid inside the gelatin 

 sulfate solution. In the case of gelatin chloride s represented the 

 concentration of chlorine ions in combination with the gelatin; 



hence - will represent the concentration of SO4 ions in combination 



with the same number of gelatin ions. 



The equilibrium equation, therefore, assumes in the case of gela- 

 tin sulfate the following form 



X (y 4-3) (^. 



«* . — = y2 (2) 



