274 



URINE. 



[CH. XII 



monium salts. The sum of the two can be taken as a 

 measure of the total amount of acid eliminated from the 

 body. The titratable acid excreted is usually measured by 

 titrating to phenol phthalein, but it is better to titrate to 

 blood reaction, i.e. P H = 7*45. By the use of the compara- 

 tor described below, this is a very simple matter. 



Palmer and Henderson* have studied the relationships 

 between reaction, volume of urine, etc. The following 

 table gives some of the results obtained in apparently 

 healthy subjects : 



They note that 



1. A increases with the hydrogen-ion concentration. 



2. With constancy in the excretion of phosphoric acid 

 the hydrogen-ion concentration varies with A. 



3. With constancy of A, the hydrogen-ion concentra- 

 tion varies as the phosphoric acid. 



4. N is fairly constant. Normally the final regulation 

 of the reaction through excretion falls upon the phosphates. 



5. The volume increases as the acidity decreases. 

 The variations in these various factors in renal disease 



* Journ. of Biol. Chem., xvii., p. 305. 



