PROPERTIES OF THE URINE. 191 



There has been considerable discussion and difference of 

 opinion among physiological chemists with regard to the 

 cause of the acid reaction of the urine. At the moment of 

 its discharge from the bladder, it is distinctly, and even 

 strongly acid ; but it will not decompose the carbonates, like 

 most acid solutions. 1 The weight of chemical authority upon 

 this point is in favor of the view that there is no free acid in 

 the urine when it is first passed, although the lactic acid, 

 the acid lactates, and perhaps some other of the organic 

 acids may be produced after emission, as the result of decom- 

 position ; but nearly all authors agree that it contains the 

 acid phosphate of soda. The phosphates exist in the fluids 

 of the body in at least three different conditions. The basic 

 phosphate of soda, for example, possesses three atoms of the 

 base, and has an alkaline reaction. In contact with carbonic 

 acid, this salt may lose one atom of the base, forming the car- 

 bonate of soda and what is called the neutral phosphate, the 

 latter, however, having a feebly alkaline reaction. In contact 

 with uric acid, the neutral phosphate may lose still another 

 atom of base, forming the urate of soda and the acid phos- 

 phate ; and according to Neubauer and Yogel, a Robin, 8 and 

 others, it is in this form that it exists in the urine, and the 

 presence of this salt is the cause of its acidity. The acid 

 phosphate of soda may or may not be associated, in the hu- 

 man subject, with the acid phosphate of lime, which ordi- 

 narily gives the intensely acid reaction to the urine of the 

 carnivora. 



Composition of the Urine. 



Regarding the excrementitious constituents of the urine 

 as a measure, to a certain extent, of the general process of 

 disassimilation, it is probably more important to recognize 

 the absolute quantity of these principles discharged in a 



1 ROBIN, Lemons sur les humeurs, Paris, 1867, p. 642. 



2 Loc, cit. 



3 Op. cit,, pp. 65, 293. 



