EXTRACTIVE MATTERS. 37 



soluble in water. Its amount is very minute ; it lias a feeble, 

 alkaline reaction, and possesses a very disagreeable and nau- 

 seous taste. It is precipitated by perchloride of tin and 

 nitrate of silver, but not by neutral or basic acetate of lead, 

 bichloride of mercury, or infusion of galls. 



Extractive matter of urme. The urine must be evaporated 

 in order to precipitate the salts as much as possible, and then 

 placed in a freezing mixture for the same purpose. When it 

 is reduced to the consistence of a thick sja'up, alcohol of '833 

 must be added to it as long as any additional precipitate is 

 thrown down. This precipitate consists of salts, and contains 

 hardly any extractive matter; it must be separated from the 

 supernatant fluid, washed with alcohol of -833, dissolved 

 in water, and precipitated again by alcohol. In this manner 

 the spii'ituous solution assumes a yelloAv colour, while the salts 

 are rendered coloirrless. By the evaporation of this yellow 

 spirituous solution we obtain the ivater-extract of urine. It 

 exists in very minute quantity. Infusion of galls produces 

 hardly any marked effect, neither does bichloride of mercury ; 

 neutral and basic acetates of lead yield a copious precipi- 

 tate. 



Spirit-extract of urine is obtained by evaporating the 

 spirituous solution to the consistence of a thick extract ; it is 

 then treated with a little anhydrous alcohol, and subsequently 

 with ether. By shaking, and the application of a gentle warmth, 

 the ether assumes a yellow colour, and a light brown matter 

 separates ; this must be washed in ether, and then treated with 

 absolute alcohol, which throws down a brown extractive matter, 

 while the alcohol assumes a nearly similar tint. This precipi- 

 tate must be washed with absolute alcohol, dissolved in water, 

 and evaporated. Its ash contains a considerable amount of 

 chlorides. Infusion of galls, bichloride of mercury, and neutral 

 acetate of lead do not aifect its solution, but basic acetate 

 of lead throws down a copious precipitate. 



Alcohol-extract of urine is obtained by the evaporation of 

 the brown alcoholic solution referred to a few lines back. On 

 the addition of anhydrous alcohol it is reduced to a yellow fluid, 

 from which urea separates on slow evaporation. After the 

 removal of this substance, we have the substance known as 

 alcohol-extract of urine. Infusion of galls, bichloride of mer- 



