178 PHYSIOLOGICAL CHEMISTRY 



4. Combined Acidity. This value may be obtained by subtracting the number 

 of cubic centimeters of N/io sodium hydroxide used in neutralizing the contents of 

 vessel B from the number of cubic centimeters of N/io sodium hydroxide used in 

 neutralizing A. The data for 100 c.c. of gastric juice may be calculated according 

 to directions given under Total Acidity, page 165. 



5. Acidity Due to Organic Acids and Acid Salts. This value may be conven- 

 iently calculated by subtracting the number of cubic centimeters of N/io sodium 

 hydroxide used in neutralizing the contents of vessel C from the number of cubic 

 centimeters of N/io sodium hydroxide solution used in neutralizing the contents of 

 vessel B. The remainder indicates the number of cubic centimeters of N/io 

 sodium hydroxide solution necessary to neutralize the acidity due to organic acids 

 and acid salts present in 10 c.c. of gastric juice. The data for 100 c.c. of gastric 

 juice may be calculated according to directions given under Total Acidity, page 165. 



