On Kreatinins. 



529 



Reducing Action of a Specimen of Kreatinin from Kreatin of Beef 



The kreatin from which this kreatinin was prepared was extracted 

 by myself from beef (62 lbs.) by Liebig's process, and I followed 

 Liebig's directions as exactly as possible in converting it into krea- 

 tinin. The product, however, required 390*2 times its weight of 

 alcohol at 15° C. for solution, and its platinum salt contained water of 

 crystallisation, so that the base does not agree in properties with that 

 described by Liebig. 



The reducing action of this base was feebler than that of the arti- 

 ficial kreatinin from the kreatin of urine. It required 3 mols. of this 

 kreatinin to reduce as much cupric oxide as 1 mol. of glucose. 



Thus, comparing the reducing action of kreatinins, we have — 



Tabular and 1 ,. . £ '. A , , 



efflorescent I ^- rea * mms from urine. 4 molecules = Z mols. glucose. 



Tabular % 1 Kreatinins from urin- 1 » 



and (3 J ary kreatin J° 



Kreatinin from kreatin of flesh 6 ,, ,, 



It is evident, therefore, that the reducing action of the natural 

 kreatinin is much greater than any of the artificial kreatinins which I 

 have examined. 



In conclusion, I think it is proved — 



(1st.) That the most active reducing agent in normal urine is the 

 urinary kreatinin. 



(2nd.) That the properties of kreatinins artificially prepared cannot 

 be considered as identical with those of the natural base ; and 



(3rd.) That there is strong presumptive evidence against the exist- 

 ence of sugar in normal human urine. 



In this paper I have confined my attention to the differentiation of 

 kreatinins by the study of their physical properties, reactions, &c. I 

 hope shortly to study the substitution products of the various sub- 

 stances I have described, with a view to the construction of rational 

 formulae, &c. 



Appendix by Professor W. N. Hartley, F.R.S. 



On the Absorption-spectrum of a Base from Urine. 



The base which Mr. G. S. Johnson has separated from urine is 

 regarded as isomeric with kreatinin artificially prepared by Liebig's 

 process ; it has therefore been considered of interest to ascertain the 

 character of its absorption-spectrum and more especially to compare 

 the specific absorptive power of the two substances. The method of 

 examination was that described in the ' Proceedings of the Royal 



