368 



Mr. G. S. Johnson. 



[June 16, 



The free reducing base is obtained from its hydro chloride by mixing 

 the concentrated aqueous solution with excess of pure lead hydrate 

 without heat, and filtering ; the alkaline filtrate by spontaneous evapo- 

 ration deposits large square plates with bevelled edges, or long efflo- 

 rescent prisms if great care is taken to avoid heating the solution of 

 the hydrochloride. The aqueous solution of the free base is alkaline 

 in reaction, intensely bitter to the taste, gives crystalline precipitates 

 with zinc chloride, mercuric chloride, and picric acid, but none with 

 silver nitrate, unless the solution be very concentrated. 



The reducing base, which is undoubtedly the natural kreatinin of 

 urine, when anhydrous, has the empirical formula C4H7N3O, but the 

 efflorescent kreatinin, obtained only when great care is taken to avoid 

 heat, has the composition C 4 H 7 I^30.2H20. After efflorescence this 

 body has the same percentage composition as the anhydrous tabular 

 kreatinin : — 



1 part by weight of the tabular kreatinin dissolves in 10' 78 parts of 

 water at 17° C. 



1 part of the tabular kreatinin dissolves in 362 parts of absolute 

 alcohol at 17° C. 



The efflorescent kreatinin .{before efflorescence) dissolves in 10*6 parts 

 of water at 14° C. The effloresced kreatinin requires 14 parts of 

 water at 14° C. for solution. 



The natural kreatinin of urine reduces cupric oxide in proportion 

 as 12 : 10 parts by weight of glucose. 



The average weight of this base passed by a healthy man in twenty- 

 four hours (as determined by weighing the spherical mercury salt 

 precipitated from the urine as above) is from 1*7 to 2*1 grams, equiva- 

 lent in reducing action upon cupric oxide to from 1*5 to 1'75 grams 

 of glucose (= 23 to 27 grains of glucose in 52*8 fluid ounces of 

 urine) . 



Therefore cupric oxide will be reduced by the normal urine in quanti- 

 ties equivalent to the reduction effected by 0'43 to 0'51 grain of glucose 

 per 1 fluid ounce. The conclusion is that the total reduction effected 

 by normal urine is accounted for by the uric acid and kreatinin which 

 it contains. 



Part II. 



The natural urinary kreatinin yields a kreatin when its dilute 

 aqueous solution is subjected to prolonged ebullition ; and this 

 kreatin, when treated by Liebig's process, is converted into kreatinin 

 hydrochloride. 



This artificial kreatinin hydrochloride differs from the hydrochlo- 

 ride of the natural kreatinin of urine, in that it crystallises from cold 

 aqueous solution in efflorescent crystals, whereas the hydrochloride of 

 the natural base is always anhydrous. 



