THE URINE. 377 



Many substances have been observed in animal urine which are not found 

 in human urine. To these belong : cynurenic acid, Ci H 7 NO 3 , occurring in 

 dog's urine and which is an oxychinolin carbonic acid ; urocanic acid (JAPPB), 

 first found in dog's urine ; damaluric acid and damolic acid (according to 

 SCHOTTEN, probably a mixture of benzoic acid with volatile fatty acids), 

 obtained by the distillation of cow's urine ; and lastly the lithuric acid, found 

 in the urinary concrements of certain animals. 



III. Inorganic Constituents of Urine. 



Chlorides. The chlorine occurring in urine is undoubtedly com- 

 bined with the bases contained in this excretion; the chief part is 

 combined with sodium. In accordance with this, the amount of 

 chlorine in the urine is generally expressed as NaCl. 



The amount of chlorine combinations in the urine is subject to 

 considerable variation. In general the quantity for a healthy 

 grown person on a mixed diet is 10-15 grms. NaCl per 24 hours. 

 The quantity of common salt in the urine depends chiefly upon the 

 quantity of salt in the food, with which the elimination of chlorine 

 increases and decreases. Abundant drinking of water also increases 

 the elimination of chlorine, which is greater during activity than 

 during rest (during night). Certain organic chlorine combinations, 

 such as chloroform, may increase the elimination of inorganic chlo- 

 rides by the urine (ZELLEB, MYLITJS, KAST). 



In diarrhoea, in quick formation of large transudations and 

 exudations, also in specially-marked cases of acute febrile diseases, 

 at the time of the crisis, the elimination of common salt is signifi- 

 cantly decreased. The elimination is abnormally increased in the 

 first days after the crisis and during the absorption of extensive 

 exudations. A diminished elimination of chlorine is found in 

 acute and chronic diseases of the kidneys accompanied with albu- 

 minuria. In chronic diseases the elimination of chlorine in general 

 keeps pace with the nutritive condition of the body and the activity 

 of the secretion of the urine. As a rule the chlorine is diminished 

 in chronic diseases. 



The quantitative estimation of chlorine in urine is most simply 

 performed by titration with silver-nitrate solution. The urine 

 must not contain either albumin (which if present must be re- 

 moved by coagulation) or iodine or bromine compounds. 



In the presence of bromides or iodides evaporate a measured quantity of 

 the urine to dryuess, fuse the residue with saltpetre and soda, dissolve the 



