276 THE URINE. 



from the urine according to the method suggested by Garrod. The 

 collected urine of twenty-four hours is heated nearly to the boiling- 

 point, and then treated with 5 or 6 grammes of neutral lead acetate 

 in substance for every 100 c.c. of the urine. As soon as the salt is 

 dissolved, the resulting precipitate is filtered off and the filtrate set 

 aside in the cold for twenty-four hours. The crystals of lead homo- 

 gentisinate are then collected on a filter and dissolved in hot water. 

 This solution gives the various reactions described above. To isolate 

 the free acid, the lead compound is decomposed with hydrogen sul- 

 phide and the filtrate carefully evaporated on a water-bath until the 

 fluid begins to darken, when it is further concentrated in a vacuum 

 to the point of crystallization. The resulting crystals are soluble 

 in water, alcohol, and ether, but are insoluble in chloroform, benzol, 

 and toluol. They melt at 146.5-147 C. 



In rare cases uroleucinic acid dioxy-phenyl-a-lactic acid 



HO.C C 



CH 

 H 



I II 

 HC C.OH 



\CH 3 .CH(OH).COOH 



also can appear in the urine. In its general reactions it resembles 

 homogentisinic acid, but does not give the iron reaction described 

 above. Unlike the latter, it reduces Nylander's solution when 

 present to the extent of 0.5 per cent, or more. It is manifestly an 

 antecedent of homogentisinic acid. 



Inosit. The origin and chemical constitution of inosit will be 

 considered elsewhere. According to Hoppe-Seyler, it may occur in 

 the urine under normal conditions, but more commonly it is found 

 in diseases which are associated with a high grade of polyuria, such 

 as diabetes insipidus, diabetes mellitus, in chronic interstitial neph- 

 ritis, etc. 



To demonstrate its presence in the urine large amounts are con- 

 centrated to a syrup, which is then extracted with four times its 

 volume of alcohol by boiling. On cooling, this extract is treated 

 with an excess of ether, when the inosit gradually crystallizes out 

 and may be recognized by its special tests (see Muscle Tissue). 



The remaining aromatic substances which have been found in the 

 urine are the kynurenic acid and urocaninic acid of the urine of 

 dogs, and the so-called lithuric acid, which has been obtained from 

 the urine of the ox. The two latter have thus far been found in 

 only one instance and need not be considered at this place. Their 

 formulae are given as : 



C 12 H 12 N 4 O 4 , urocaninic acid. 

 Ci 5 H 19 NO 9 , lithuric acid. 



