1250 CREATININE. 



its separation from solutions. It crystallizes in warty lumps 

 composed of aggregated masses of prisms, or fine needles. 



This compound is formed when a concentrated neutral solu- 

 tion of the zinc salt is added to a not too dilute solution of 

 creatinine, and since it is almost insoluble in alcohol it is fre- 

 quently convenient to employ alcoholic rather than aqueous 

 solutions of the two substances. 



Preparation. This does not admit of any useful brief description. 



Apart from the characteristic formation of the compound 

 with zinc chloride, creatinine yields several well-marked reac- 

 tions, of which the following are the more striking. 



1. WeyVs reaction. To the suspected solution a few drops 

 of very dilute sodium nitro-prusside [Na 2 (NO)FeCy 5 ] are 

 added, and then, drop by drop, some dilute caustic soda. If 

 creatinine is present a fine but transient ruby-red colour is 

 obtained which speedily passes into yellow. If the solution is 

 now acidulated with acetic acid and boiled it turns at first 

 greenish and finally blue. This last colour is due to the for- 

 mation of Prussian-blue. Weyl's reaction is extremely delicate 

 and suffices to detect -0287 p.c. of creatinine in pure solution or 

 •066 p.c. in urine. 



When applied to urine the absence of acetone should be 

 ascertained, since it also gives a similar ruby-red colour, but no 

 subsequent blue can be obtained from it, and the solution when 

 yellow turns red again on the addition of strong acetic acid. 

 Hydantoin or methyl-hydantoin also yields the red coloration. 



2. Jaffe's reaction. On the addition of an aqueous solution 

 of picric acid and a few drops of dilute caustic soda, an intense 

 red coloration is produced. This suffices to detect -1 part of 

 creatinine in 5000 of water. Acetone alone gives a similar 

 coloration but to a comparatively very feeble extent. 



By prolonged boiling of creatinine with Fehling's fluid, 

 reduction takes place, but there is no simultaneous separation of 

 cuprous oxide, and it appears that creatinine may prevent the 

 separation of the oxide when the reduction is due not to itself 

 but to such a substance as dextrose. 



12. Lysatine. C 6 H 13 N 3 



2" 



This most interesting substance has been recently obtained 

 during the decomposition of casein by boiling with hydrochloric 

 acid and stannous chloride and was first separated from the 

 mother liquor left after the preparation of lysine (see p. 1245). 

 The methods of obtaining lysatine admit of no suitably concise 

 description. It is a white crystalline solid, soluble in water and 

 crystallizable from its aqueous solution by the addition of some 

 alcohol and ether. It forms a well-characterized double salt with 



