1867.] 



Extractive Matters of Urine. — Part I. 



87 



from the other constituents is worth mentioning. He added an excess of 

 acid to urine, and the uric acid which separated on standing he treated with 

 boiHng alcohol, which left the acid undissolved, and, after filtration and 

 evaporation, gave a residue consisting of a reddish-brown extractive matter, 

 which had a bitter aromatic taste, and, when warmed, exhaled a urinous 

 odour. The colour of its watery solution was exactly like that of urine. 



In his elaborate memoir on urine, Lehmann * makes some remarks on 

 the properties of the extractive matter of urine and the best method of pre- 

 paring it. For the purpose of obtaining it in a state of purity, he submitted 

 urine to congelation, and evaporated the concentrated liquid in vacuo, em- 

 ploying afterwards alcohol and ether for the purpose of extracting it from 

 the residue. No part of the process described by him would induce any 

 extensive decomposition of the substance under examination. On the other 

 hand, it is very doubtful whether it was quite free from impurities, since he 

 attributes to the coloured extractive matter {fdrhender Extractivstoff) of 

 urine the property of inducing decomposition in urea, and consequently in 

 urine also — a property which it certainly does not possess when pure, how- 

 ever liable it may itself be to decomposition. The putrefaction of urine, 

 which manifests itself by the conversion of the urea into carbonate of am- 

 monia, must be caused by some other body. The extractive m.atter does 

 not act as a ferment, which may indeed be inferred from the very small 

 quantity of nitrogen contained in it. The disagreeable odour which the 

 watery solution of Lehmann' s substance began to exhale when exposed to 

 the air also points to some impurity. Its acid reaction he attributes to an 

 admixture of lactic acid, which was generally supposed to be contained in 

 urine, until its entire absence was proved by the experim.ents of Liebig. 

 Lehmann's observations regarding its other properties, as, for instance, the 

 changes of colour produced in its watery solution by various reagents, are, 

 however, remarkably correct. 



Lehmann, as well as Berzelius, found the substance to which healthy 

 urine owes its colour to be completely soluble in water. Subsequently, 

 however, most of the attempts which were made to isolate the colouring- 

 matter of urine ended in the separation of substances quite insoluble in 

 water. These must in all cases have been products of decomposition ; for 

 I consider it quite certain that all colouring-matters derived from urine 

 which are insoluble in water are not contained as such in the secretion, pro- 

 vided the latter is in its normally acid state. In the experiments of 

 Scherer f and Ilarley J, various products of decomposition of this kind 

 seem to have been obtained. Scherer, not being satisfied with the methods 

 of preparing and separating the extractive matters given by Berzelius, 

 adopted one of his own, which yielded a brown humus-like substance, in- 

 soluble in water, but soluble in alcohol and alkalies. Scherer calls this 



Journal fiir praktisehe Cliemie, B. xxv. S. 1. 

 t Annalen cler Cheniie unci Pliarmacie, B. h'ii. S. 180. 

 X Pharmaceutical Journal, vol. xii. p, 243. 



