URINE. isi 



into the circulation, absorb, and remove from the organism, 

 through the urinary channels, all the soluble salts and other 

 substances which do not belong to the constitution of the blood; 

 so that, finally, only those substances remain in the organism 

 which exist in chemical combination with the constituents of 

 the blood, and which, therefore, are incapable of being secreted 

 by the healthy kidneys. 



" I have convinced myself, by careful and minute examina- 

 tions, that urine emitted after drinking a copious amount of 

 water, invariably contains a somewhat larger amount of salts 

 than the water which has been drunk ; whilst the amount of 

 phosphates contained in the last emitted portions of the urine 

 is extremely minute, and no longer detectible by the ordinary 

 tests. It is therefore obvious that all the salts, without excep- 

 tion, contained in the urine, are to be considered as accidental 

 constituents of the blood, which are excreted and removed from 

 the organism precisely because they no longer form a part of the 

 normal constitution of the blood. The phosphates emitted with 

 the urine were, previously, constituents of substances which have 

 been decomposed in the vital processes, or they existed as con- 

 stituents of the blood, but upon its transformation into living 

 tissues they were not admitted into their composition, not being 

 required for their constitution. 



"Now, among the products of the vital processes, which, 

 together with the soluble phosphates, are removed from the or- 

 ganism through the urinary organs and channels, there are two 

 organic acids, namely, uric acid and hippuric acid, both possess- 

 ing the property of combining with the soda or potash of the 

 alkaline phosphates, and acquiring in the combination a higher 

 degree of solubility than they possess, per se, at the common 

 temperature of the body. It is obvious that by the accession 

 of these two acids, and by their action upon the phosphates 

 of soda, an urate and hippurate of soda must be formed 

 on the one hand, and an acid phosphate of soda on the 

 other ; and that, consequently, the urine must acquire an acid 

 reaction. 



But the presence of these two acids in the urine is not the 

 only cause of its acid nature; there exists another cause which 

 tends powerfully to maintain and increase it. 



" According to the preceding remarks we ought to find in 



