URINE. 105 



ACIDITY OF THE URINE. 



It is quite generally understood that the degree of acidity 

 of the urine is due to the excess of the dihydrogen (acid) 

 over the monohydrogen phosphates, the relation to the 

 total phosphates usually being about 60 per cent of the 

 former to 40 per cent of the latter. Based upon this view, 

 the methods for the quantitative determination of the acidity 

 have consisted in the estimation of the total P 2 5 and the 

 P 2 5 present in the form of the acid phosphates, and from 

 which the degree of relative acidity of the urine was derived. 

 Many difficulties arise in the procedure for the quantitative 

 separation and determination of the two types of phosphates, 

 and the present methods have been shown to be full of 

 errors. Theoretical objections have also been raised, and 

 attempts made to show that the ' ' organic " acidity, as opposed 

 to the " mineral" (phosphate) acidity, plays a not incon- 

 siderable role in determining the total acidity. How un- 

 important the estimation of the organic acidity really is 

 can be understood when it is" noted that organic acids appear- 

 ing in a solution of mixed phosphates are able to remove the 

 base from the monohydrogen phosphates, and thus pro- 

 duce an almost equivalent increase in the quantity of the 

 acid phosphates. The presence of the organic acids, there- 

 fore, only serves to increase the acid phosphates, and the 

 latter still remain theoretically the most accurate indica- 

 tion of the total acidity. The technical difficulties have 

 led to the reliance upon the method of direct titration of 



the urine with r^ alkali. This procedure has the advantage 



of rapidity and possesses some value, perhaps, where com- 

 parisons only are required. Absolute values in the present 

 state of the question are unattainable. 



