On Kreatinins. 



527 



efflorescent. If repeated re-crystallisations by spontaneous evapora- 

 tion from cold aqueous solution be made, the kreatinin tends 

 ultimately to assume the efflorescent form. 



By redissolving at 60° C, we may, at any time, cause the production 

 of temporarily tabular kreatinin /3, which swings back to the per- 

 manently efflorescent state after one or two re-crystallisations from 

 cold aqueous solution ; or by redissolving in water at 100° C, we may 

 produce tabular kreatinin a, which re-crystallises in the same form 

 indefinitely from cold aqueous solution. 



It is extremely remarkable, however, that the efflorescent kreatinin 

 is obtained by dissolving tabular kreatinin x in water at 60° C, and 

 then evaporating spontaneously. 



Condition of the Two Molecules of Water in the Efflorescent Kreatinin. 



Although this water behaves like the water of crystallisation in an 

 efflorescent salt in many respects, and although it does not appear in 

 the gold salt formed by the efflorescent kreatinin, yet there are 

 reasons for supposing that either the kreatinin in the efflorescent 

 kreatinin differs from the tabular anhydrous kreatinin ; or else that 

 the water is more closely combined with the kreatinin than ordinary 

 water of crystallisation. For instance— 



1st. The solubility in water of the efflorescent kreatinin before 

 efflorescence is the same as that of the anhydrous tabular kreatinin. 



2nd. When re-crystallised by evaporation of its cold solution in vacuo 

 after being dissolved at the boiling temperature, anhydrous tabular 

 kreatinin is produced. 



3rd. There is difficulty in forming a platinum salt of efflorescent 

 kreatinin, none in forming the platinum salt of the tabular kreatinin. 



4th. When re- crystallised from boiling alcoholic solution, the 

 efflorescent kreatinin forms needle-shaped crystals exactly resembling 

 the original base, and entirely different from those which are produced 

 in the alcoholic solution of the tabular kreatinin. 



Cupric Oxide Reduction effected by the Tabular Kreatinin from Urinary 



Kreatin. 



10*8 c.c. of a solution containing O'I/Sd gram of tabular kreatinin a 

 from kreatin of urine in 60 c.c, were required to decolourise 40 c.c. of 

 Pavy's ammoniacal cupric solution (= 0'02 gram of glucose), i.e. — 



10 parts by weight of glucose reduce as much CuO as 16 parts by 



weight of kreatinin (tabular a), or 

 2 mols. of glucose are equivalent to 5 mols. of kreatinin in reducing 



action upon CuO. 



A specimen of tabular kreatinin (i from urinary kreatinin was 

 found to have exactly the same reducing action as the above. 



