HENDERSON, COHN, CATHCART, WACHMAN, AND EENN 467 



per gm. of gluten, to give a conductivity of approximately 200 to 

 100 cc. of water. This may now be used in further study of the data 

 upon conductivity. For this quantity, plus the electrical conduc- 

 tivity of the solution of acid or alkali added to the gluten, minus the 

 electrical conductivity of the resulting solution, may be taken as a 

 roughly approximate measure of the quantity of electrolyte in union 

 with protein. It is, however, a measure which cannot be directly em- 

 ployed for comparison of the acid systems with the alkaline systems, 

 because of the considerable difference in conductivity of hydrochloric 

 acid and sodiun hydroxide. And of course the various salts of the 

 original gluten are also not equal in conductivity to the acid, to the 

 alkali, or to each other. 



The results of such calculations of the conductivity of electrolytes 

 in union with gluten are collected in Table VI. It may easily be seen 

 that the data vary in a regular and intelhgible manner. 



IV. 



In the light of the above facts the swelling of gluten in solutions of 

 acid and alkalies may now be considered. The data of Table VII in- 

 clude observations upon the weight of the wet, swollen, coherent mass, 

 upon the weight of dry gluten contained therein, as well as calcula- 

 tions of the amount of gluten dissolved and of the ratio of wet gluten 

 to dry material contained within it (the true swelling) . 



Quantitatively the results are not at all points satisfactory. The 

 following conclusions are possible. First, the weight of swollen gluten 

 bears no relation to the true swelKng (hydration) because of the 

 marked variations in the quantity of protein dissolved. Second, it 

 Ijears no direct relation to the hydrogen ion concentration, except 

 when quantities of gluten and solution are kept constant. Third, 

 the chief factor in determining the weight of swollen gluten is the quan- 

 tity of protein which has been dissolved away from it. Fourth, the 

 amount of gluten dissolved is greater the greater the acidity. Fifth, 

 the true swelling of gluten is greater the greater the acidity. There 

 also seems to be a tendency for the true swelling of gluten to increase 

 as the relative quantity of gluten increases. This corresponds to a 

 relatively greater amount of electrolyte present in the swollen mass. 



