678 URINE. 



as well as in urine in leucaemia. BALKE gives C 4 H 6 N 3 as the probable formula 

 for episarkine. It is nearly insoluble in cold water, dissolves with difficulty in 

 hot water, but may be obtained therefrom as long fine needles. Episarkine does 

 not give the xanthine reaction with nitric acid, or WEIDEL'S reaction. With 

 hydrochloric acid and potassium chlorate it gives a white residue which turns 

 violet with ammonia. It does not form any insoluble sodium compound. The 

 silver compound is difficultly soluble in nitric acid. Episarkine is possibly 

 identical with epiguanine. 



HN CO 



Epiguanine, C 6 H 7 N 5 O, 7-methylguanine, H 2 N.C C.N.CH 3 , was first pre- 



L, 



pared from the urine by KRUGER. 1 It is crystalline and difficultly soluble in 

 hot water or ammonia. It crystallizes from a hot 33-per cent caustic-soda solu- 

 tion on cooling in broad shining crystals and dissolves readily in hydrochloric or 

 sulphuric acid. It gives a characteristic chloroplatinate crystallizing in six-sided 

 prisms. It is precipitated neither by basic lead acetate nor by basic lead ace- 

 tate and ammonia. Silver nitrate and ammonia give a gelatinous precipitate. 

 It responds to the xanthine test with nitric acid and alkali. Acts like episarkine 

 with WEIDEL'S test according to FISCHER. 



In preparing alloxuric bases from the urine, the fluid is supersaturated with 

 ammonia and precipitated by a silver-nitrate solution. The precipitate is then 

 decomposed with sulphuretted hydrogen. The boiling-hot filtrate is evaporated 

 to dryness and the dried residue treated with 3-per cent sulphuric acid. The 

 purine bases are dissolved, while the uric acid remains undissolved. This filtrate 

 is saturated with ammonia and precipitated by silver-nitrate solution. If instead 

 of precipitating with silver solution we desire to precipitate, according to KRUGER 

 and WULFF, with copper suboxide, the urine may be heated to boiling, and imme- 

 diately are added, successively, 100 cc. of a 50-per cent sodium-bisulphite solu- 

 tion and 100 cc. of a 12-per cent copper-sulphate solution for every liter of urine. 

 The thoroughly washed precipitate is decomposed with hydrochloric acid and 

 sulphuretted hydrogen. The uric acid remains in great part on the filter. Further 

 details in regard to the treatment of the solution of the hydrochloric-acid com- 

 pounds may be found in KRUGER and SALOMON. 2 



Quantitative Estimation of Purine Bases according to SALKOWSKI. S 

 400-600 cc. of the urine free from protein are first precipitated by mag- 

 nesia mixture and then by a 3-per cent silver-nitrate solution as described 

 on page 675. The thoroughly washed silver precipitate is decomposed 

 by sulphuretted hydrogen after being suspended in 600-800 cc. of water 

 with the addition of a few drops of hydrochloric acid. It is heated to 

 boiling and filtered hot, and finally evaporated to dryness on the water- 

 bath. The residue is extracted with 20-30 cc. of hot 3-per cent sul- 

 phuric acid and allowed to stand twenty-four hours; the uric acid is 

 filtered off, washed, the filtrate made ammoniacal, and the purine bodies 

 again precipitated by silver nitrate, the precipitate collected on a small 

 chlorine-free filter, washed thoroughly, dried, carefully incinerated, 

 the ash dissolved in nitric acid, and titrated with ammonium sulpho- 



1 Arch. f. (Anat. u.) Physiol., 1894; Kriiger and Salomon, Zeitschr. f. physioL 

 Chem., 24 and 26. 



2 Zeitschr. f. physiol. Chem., 26, and also Hoppe-Seyler-Thierfelder's Handbuch, 

 8. Aim 1 ., 188.- 



3 Pfliiger's Arch., 69. 



