CARNIN. 413 



The solution is diluted with four parts of water, stirred thoroughly, 

 and set aside for 3-6 hours. The uric acid is thus precipitated, and 

 is then collected on a small filter, washed with water, acidulated with 

 sulphuric acid, then with pure water. Then it is transferred to the 

 dish in which it was precipitated, dissolved in a little pure sodium 

 hydrate (e natrio), strongly acidulated with hydrochloric acid, and 

 evaporated to a few c.c. After standing one hour it is filtered 

 through Ludwig's glass-wool filter, washed with HCl-water, then 

 with water, finally with alcohol and ether, dried at 110°, and 

 weighed. The filtrate and wash-water are combined, and a correc- 

 tion is made for the solubility (1 : 16,000) of uric acid. This correc- 

 tion is added to the weighed amount. The results obtained by this 

 method are excellent. The separation from guanin and xanthin is 

 complete. 



Carnin, CyHjN^Oj, was isolated in 1871 from American meat 

 extract by Weidel, but it has not been obtained from muscle tissue 

 itself. Balke, however, has isolated it from fresh horse-meat extract. 

 It has also been obtained from yeast liquors by Schiitzenberger, and 

 Pouchet claims to have isolated it from urine, but has not offered 

 sufficient evidence on this point. Salomon (1893) obtained a body 

 resembling carnin from leuksemic urine. 



It can be separated from the meat extract by the following method 

 originally employed by Weidel : The extract is dissolved in six or 

 seven parts of warm water, then concentrated baryta water is added, 

 avoiding, however, an excess. The filtrate is precipitated by basic 

 lead acetate. The precipitate is collected, thoroughly washed and 

 pressed, and finally it is repeatedly extracted with a large quantity 

 of boiling water. The carnin lead salt is thus dissolved out ; the 

 filtrate, after removal of the lead by hydrogen sulphid, is evaporated 

 to a small volume. The concentrated solution thus obtained is 

 treated with silver nitrate, which gives a precipitate of silver chlorid 

 and of the silver salt of carnin. By treatment with ammonium hy- 

 drate the silver chlorid can be completely removed from the precipi- 

 tate, whereas the silver compound of carnin is insoluble in that 

 reagent. To obtain pure carnin the silver salt is decomposed with 

 hydrogen sulphid, and the filtrate, after purification by bone-black, 

 is evaporated to crystallization. According to Weidel, carnin forms 

 about 1 per cent, of the meat extract. Kemmerich (1893) has found 

 only one-quarter of 1 per cent., or even less. The amount, there- 

 fore, varies considerably, and may be very small in the fresh extract. 



Carnin forms white crystalline masses which on drying become 

 loose and chalk-like. It is very difficultly soluble in cold water, 

 easily and completely in boiling water, and recrystallizes on cooling. 

 It is insoluble in alcohol and ether. The taste is decidedly bitter, 

 and the reaction is neutral. The base is not precipitated by neutral 



