136 



Mr. E. Scliuiick on a Crystalline 



[Recess^ 



urostealith) . In no recorded instance was the fatty matter contained in 

 the secretion in a state of true sohition. 



The accounts which are given of the physical and chemical properties of 

 the fatty matters of urine are extremely vague, and quite insufficient to 

 enable us to identify them, so that it may be concluded that in most cases 

 the quantity obtained was extremely small. Dr. Beale has, indeed, shown 

 that the fatty matter which accumulates in the epithelial cells, passed with 

 the urine in some cases of fatty degeneration of the kidney, contains 

 cholesterine ; and Berzelius and Lehmann state that urine, when distilled 

 with the addition of sulphuric acid, yields butyric acid ; but in other 

 respects our ignorance is almost complete. None of the works devoted to 

 the subject of urine contain a hint which would lead one to suppose that 

 fatty matter in any form is a constituent of the ordinary healthy secretion. 



These few words will probably suffice to give an idea of the present state 

 of our knowledge on this subject from a chemical point of view. 



The discovery of which I em about to give an account was a result of 

 the examination of the colouring and extractive matters of urine with which 

 I have been occupied for some time, and which forms the subject of several 

 Papers already communiccited to the Royal Society. In the course of my 

 experiments, I observed on several occasions, mixed with the urinary ex- 

 tractive matters, drops of a brown or yellow oil, the appearance of which 

 I could not account for, since it was difficult to conceive how fat of any 

 kind could be deposited from watery solutions of these extractive matters, 

 which generally have an acid reaction ; unless, indeed, it was assumed either 

 that it was a product of decomposition, or that the extractive matters possess 

 the properly of effecting the solution or suspension of fatty matter in water. 

 On one occasion there was deposited during the evaporation of a watery 

 solution of urian (the extractive matter soluble in ether) a quantity of fatty 

 acid, from which I prepared a baryta-salt soluble in boiling alcohol, and 

 crystallizing from this solution in smiall scales. Traces of a fat-like sub- 

 stance were almost always obtained on treating watery solutions of the ex- 

 tractive matters with animal charcoal, filtering, treating the charcoal with 

 boiling alcohol, and evaporating the alcoholic liquid. Animal charcoal also 

 effected the separation of a small quantity of fatty matter from urine itself, 

 and this circumstance led me to devise a plan for procuring a quantity 

 sufficiently large to enable me to determine its chief properties. This 

 method I shall now proceed to describe. 



Ordinary healthy urine, having been filtered so as to separate all insoluble 

 matter, is passed in successive portions through purified animal charcoal 

 contained in a common percolating apparatus. The percolaling liquid 

 appears quite colourless, and devoid of the usual odour of urine. K large 

 quantity of urine may thus be passed with the same effect through a small 

 quantity of charcoal ; but at last there arrives a point at which the char- 

 coal, though apparently retaining its decolorizing and deodorizing power 

 undiminished, suffers the liquid to pass through with extreme slowness 



