470 URO-GENITAL SYSTEM. 



ratio between the degree of animal heat and the amount of 

 urea eliminated (Hepp and Hirtz). 1 



The remaining 35 grms. of anhydrous urine (half the 

 amount eliminated in a day) is distributed as follows : 



There are 15 grms. of matters called extractive, that is, 

 products of incomplete combustion of the albuminoids : to 

 this class belong creatine, creatinine, etc., but the most inter- 

 esting of this class is uric acid, not found in large quantity, 

 it is true; but which, under certain circumstances, can be 

 accumulated to a large extent, or be retained in the tissues 

 (uric acid diasthesis ; gout; tophus of urateof soda). In the 

 normal state this substance exists in proportion to the urea, 

 as 1 is to 30 ; that is to say, that 1 grm. is found in the urine 

 of 24 hours. Its especial characteristic consists in its sparing 

 solubility in water, which dissolves only ^uW f ^ ts weight. 

 On account of its difficult solubility we cannot explain how 

 uric acid exists in solution in the urine ; it may be in com- 

 bination with soda as urate of soda; yet, as this latter is 

 scarcely any more soluble than uric acid (y^Vcr)* we mu st 

 suppose that uric acid or the urates are dissolved by the aid 

 of the acid phosphate of soda (that which gives to urine 

 its acid reaction), or by that of the coloring matter. It is 

 known that if urine be allowed to stand while exposed to the 

 air, a species of lactic acid fermentation ensues, by which a 

 large portion of the coloring matter seems to be destroyed 

 and uric acid to be formed. Among many of the herbivora 

 an analogous acid, Mppuric acid, apparently replaces the uric 

 acid; this former acid is composed of benzoic and glyco- 

 cholic acid : in fact, man can make this acid appear in his 

 urine by the ingestion of benzoic acid ; glycochol or sugar of 

 gelatine is by this means provided by the metamorphosis of 

 the connective tissue. 



There now remain but 20 grms. of anhydrous urine for 

 whose composition we must account ; these 20 grammes are 

 represented by the salts, of which chloride of sodium forms 

 8 parts, and various other salts 12 parts (sulphates, phos- 

 phates, lactates, &c.). The base of these salts is mostly soda ; 

 there are also some salts of lime held in solution by means of 

 an excess of acid. Alkaline urine, as from the herbivora, 

 for instance, is turbid ; and horse-urine is employed as a type 



1 See Art. " Fievre," in Vol. XVI. of the " Nouveau. Diet, de 

 Medecine et de Cliirurgie Pratiques." 



