902 



APPENDIX. 



what bitter taste, is soluble in cold, extremely ^ soluble in hot water, is less soluble in 

 absolute than in dilute alcohol, and is soluble in ether. 



It is a very weak base, scarcely neutralizing the weakest acids. It forms crystal- 

 line compounds with sulphuric, hydrochloric, and nitric acids. 



[FIG. 241. 



Crystals of Kreatin and Kreatinin. a, crystals of kreatin; b, crystals of kreatinin ; c, crystals of 

 chloride of zinc and kreatinin.] 



Preparation. From extract of muscle by precipitating completely with basic 

 lead acetate, and crystallizing out the kreatin, mixed with kreatinin. From this 

 latter it is separated by the formation of the zinc-salt of kreatinin, kreatin not 

 readily yielding a similar compound. 



Kreatin may be converted into kreatinin under the influence of acids, the transformation 

 being one of simple dehydration. 



Kreatin may be decomposed into sarcosin (methyl-glycin) and urea: 



C 4 H 9 N 3 2 + H 2 = C 3 H 7 N0 2 + CH 4 N 2 ; 



it may be formed synthetically l by the action of sarcosin and cyanamide : 

 C 3 H 7 N0 2 + CH 2 N 2 = C 4 H 9 N 3 0. 



Sarcosin is glycin in which one atom of hydrogen has been replaced by the alcohol 

 radicle methyl, thus : 



Glycin g 2 ^ 1 becomes 

 like glycin, sarcosin has not been found in free state in the body. 

 Kreatinin. C 4 H 7 N 3 0. 



This, which is simply a dehydrated form of kreatin, occurs normally as a con- 

 stant constituent of urine and of muscle extract. It crystallizes in colorless shining 

 prisms [Fig. 241, 6], possessing a strong alkaline taste and reaction. It is readily 

 soluble in cold water (1 in 11.5), also in alcohol, but is scarcely soluble in ether. It 

 acts as a powerful base, forming with acids and salts compounds with crystallize 

 well. Of these the most important is the salt with zinc chloride (C 4 H 7 N 3 0) 2 

 ZnCl 2 . It is formed when a concentrated solution of the chloride is added to a not 

 too dilute solution of kreatinin. Since the compound is very little soluble in alcohol 

 it is better to use alcoholic rather than aqueous solutions. It crystallizes in warty 

 lumps composed of aggregated masses of prisms or fine needles. [Fig. 241, c. } 



Preparation. Either by the action of acids on kreatin, or from human urine by 

 concentrating and precipitating with lead acetate ; in the filtrate from this a second 



1 Sitzungsber. d. Bayerisch. Akad., 1868, Heft 3, S. 472. 



