1867.] 



Fattij Acid from Urine. 



137 



only, and the latter, after having percolated, appears rather milky, from a 

 small quantity of white matter suspended in it. At this point it .is advi- 

 sable to discontinue the percolation of urine and to commence washing the 

 charcoal with water. This is continued until every trace of chlorides and 

 phosphates is removed, and the charcoal is then laid to dry, either in the 

 air or at a moderate temperature in a stove. When dry the charcoal is treated 

 with boiling alcohol, to which it communicates a bright yellow colour like 

 that of urine itself, the liquid is filtered, and the process is repeated until 

 the alcohol acquires only a faint yellow colour. To arrive ac a point at 

 which it would appear quite colourless seemed to me almost impossible. 

 The whole of the alcoholic liquid, which in any case is considerable in 

 quantity, is now evaporated either spontaneously or at a moderate tem- 

 perature. The brown syrupy residue which is left on evaporation is mixed 

 with water, which leaves undissolved a quantity of dark-brow^n semifluid 

 fatty matter to be separated by filtration. The Hquid, which has a yellow 

 colour, contains in solution a crystallized organic substance, the occurrence 

 of which in urine has not hitherto been observed. It also contains, pro- 

 vided the evaporation of the alcoholic liquid was conducted spontaneously, 

 a quantity of indican ; for on the addition of sulphuric or hydrochloric 

 acid, it deposits flocks of indigo-blue — a reaction which, however, ceases to 

 be produced after the solution has stood for some time in a warm place. 

 Its colour is mainly due to the ordinary extractive matters of urine which 

 it contains. 



The fatty matter which is left undissolved by the water has a dark-brown 

 colour and a strongly urinous odour. In order to purify it, it is dissolved in 

 alcohol, and the filtered liquid is evaporated. The residual fatty mass is 

 pressed between blotting-paper, in order to absorb as much as possible the 

 more fluid portion, and it is then redissolved in alcohol. The alcoholic 

 solution is agitated with a little animal charcoal, which deprives it of some 

 of its colour, then filtered and evaporated, when it leaves a brownish-yellow 

 residue, which still retains some of the odour just referred to. By treat- 

 ing it with very dilute spirits this odour, as well as the yellow colour, which 

 seem to belong to the same body, are removed, and an almost white solid 

 fat is left undissolved*. This may be still further purified by dissolving 

 it in a boiling solution of carbonate of potash. The soap, which separates 

 on cooling, is filtered off, w^ashed with a solution of carbonate of potash, and 

 decomposed with acid. The fatty acid which separates is now quite 



The jSItered alcoholic liquid leaves on evaporation a semifluid, yellow, amorphous 

 fatty mattei*, having a peculiar urinous odour. When heated on platinum-foil this sub- 

 stance becomes more fluid, gives oif a strong smell like that of burning fat, and then 

 burns with a bright flame. It dissolves easily in caustic soda-lye, and the solution 

 froths on being boiled. Its alcoholic solution is yellow, reddens litmus-paper more 

 strongly than the solution of the crystalline acid, and gives with acetate of lead a dirty- 

 yellow flocculent precipitate, which is somewhat soluble in alcohol, since the liquid, 

 when boiled and filtered boiling hot, deposits a quantity of white crystalline grains 

 accompanied by a few thin prismatic crystals. 



VOL. XVI, L 



