POTENTIOMETRIC METHOD 



77 



of protein was introduced into 2 and the potential again deter- 

 mined. The difference between the two readings, in accordance 

 with the Nernst formula, affords a measure of the number of 

 CI ions bound by the protein. The other concentration-cell 

 was the ordinary gas-chain. 



As before, the potential of the chain was first measured for a 

 known concentration of acid in 2, then a weighed amount of 

 protein was added to the acid and the potential of the chain was 

 again determined, the difference between the two readings afford- 

 ing, in this case, a measure of the diminution in the number of 

 H ions due to the introduction of the protein. When it is desired 

 to determine the base-binding capacity of the protein, the latter 

 is added to the alkali in 3, instead of to the acid in 2. 



The following are representative of the results obtained by 

 Bugarzsky and Liebermann. In the tables G signifies the number 

 of grams of protein in 100 cc. of solution, p the percentage of 

 acid or base bound by the protein, and r the ratio. 



grams of acid or base bound 

 grams of protein 



I. GAS-CHAIN. EGG ALBUMIN DISSOLVED IN 0.05 A^ HCI 



II. MERCURY-CHAIN. EGG ALBUMIN DISSOLVED IN 0.05 N HCI 



