APPENDIX TO CHAPTER V 163 



mg. ; under bad conditions to within I mg. Weber [1908] puts the 

 error at 4 per cent. Rona [1910] purifies solutions by means of 

 colloidal ferric hydroxide, which does not adsorb any creatinine. 



The estimation of creatine and creatinine in meat and meat extracts 

 by Folin's method has been carried out by Baur and Barschall 

 [1906], Grindley and Woods [1906], Emmett and Grindley [1907], 

 Chapman [1909] and Cook [1909]. It affords a means of distinc- 

 tion from the very similar commercial yeast extracts which contain 

 no creatine or creatinine (at most O'o8 per cent.). 



Chapman [1909], for the estimation of creatine + creatinine, 

 mixes 10 c.c. of a 10 per cent, meat extract solution with 10 c.c. of 

 normal hydrochloric acid, and heats to 120 in an autoclave for half 

 an hour. After cooling to 20, 30 c.c. of saturated picric acid and 

 i 5 c.c. of 10 percent, sodium hydroxide are added ; after five minutes 

 the solution is made up to 500 c.c. and estimated colorimetrically. 



For the actual isolation of creatinine from small quantities of ex- 

 tracts, see Micko [1910]. 



Glycocyamine and Glycocyamidine. 



Glycocyamine, C 3 H 7 O 2 N 3 , forms anhydrous crystals which gradually 

 decompose above 220 without melting. At 14 -5 i part dissolves 

 in 218 parts of water (Ramsay). The substance is a stronger base 

 than creatine (dissociation constant 2-32 x io" u at 4O'2; Wood [1903, 

 under creatine]) and yields a hydrochloride, C 3 H 7 O 2 N 3 . HC1, m.p. 191 ; a 

 picrate, C 3 H 7 O 2 N 3 . C 6 H 3 O 7 N 3 , m.p. 1 99-200, very little soluble in water ; 

 a readily soluble platinichloride, (C 3 H 7 O 2 N 3 ) 2 . H 2 PtCl 6 . 2H 2 O, m.p. 

 198-200, and an aurichloride, m.p. 173. Glycocyamine solutions give 

 with copper acetate a pale blue precipitate (C 3 H 6 O 2 N 3 )2Cu . H 2 O, 

 and with HgCl 2 in the presence of sodium acetate a white precipitate; 

 no compound with zinc chloride is known. 



Glycocyamidine, C 3 H 5 ON 3 , is formed by heating glycocyamine 

 hydrochloride to 160-170 ; small quantities are more readily prepared 

 by heating I grm. of this hydrochloride with 5 c.c. of concentrated 

 hydrochloric acid to 140 in a sealed tube. The free base is obtained 

 by boiling the resulting hydrochloride with freshly precipitated lead 

 hydroxide. An alcoholic solution (but not an aqueous solution) of 

 glycocyamidine hydrochloride gives with alcoholic zinc chloride a 

 crystalline salt (C 3 H 6 ON 3 ) 2 ZnCl 2 . The picrate, C 3 H 5 ON 3 . C 6 H 3 O 7 N 3 , 

 forms yellow needles ; m.p. 206-210. The normal aurichloride is very 

 soluble and easily changes to the less soluble gold salt C 3 H 5 ON 3 . AuCl 3 ; 

 m-P- i 53-1 54 (Korndbrfer [1905]). 



II 



