On Kreaiinins. 



517 



Or 1 mol. of glucose is equal to 3 mols. of kreatinin from kreatin of 

 flesh in reducing action upon cupric oxide. 



"Whereas 1 mol. of glucose is equal to 2 mols. of the natural kreati- 

 nin of urine in cupric oxide reducing power. 



But the important practical deduction which I draw from the above 

 data is this — that the natural kreatinin of urine is responsible for 

 the bulk of the reducing action exerted by normal human urine, and 

 further that, in my belief, the whole cupric oxide reduction effected 

 by that secretion may be accounted for by uric acid and kreatinin. 



Taking 1500 c.c. (= 52*8 fluid ounces) as the average volume of 

 urine passed by a healthy man in the twenty-four hours, and 6 to 

 7 grams per litre as the average weight of the spherical mercury salt 

 of kreatinin yielded by the normal secretion, then, as the spherical 

 mercury salt contains 20 per cent, of kreatinin (C^H^-IS^O), the weight 

 of anhydrous kreatinin passed in twenty-four hours by a healthy man 

 will vary between 1*8 and 21 grams. And as 12 grams of the reducing 

 kreatinin of urine are equivalent to 10 grams of glucose in reducing 

 action upon cupric oxide, it follows that the cupric oxide reduction 

 effected by the urinary kreatinin in twenty-four hours is equivalent 

 to that which would be produced by 1*5 to 175 grams of glucose, i.e., 

 by from 23 to 27 grains of glucose in 52*8 fluid ounces of urine. 



Accordingly cupric oxide is reduced by the kreatinin of normal 

 urine in the same degree as if the secretion contained from 0*43 to 

 0'51 grain of glucose in each fluid ounce. 



But the total cupric oxide reduction effected by normal human 

 urine is equivalent to from 0*6 to 0'8 grain of glucose per 1 fluid 

 ounce, and of this total reduction one-fourth has been shown by 

 Dr. Pavy to be due to uric acid. Therefore the total reduction is 

 accounted for by the conjoined action of the uric acid and kreatinin. 



I can only attribute the little importance which has hitherto been 

 attached to the reducing action of urinary kreatinin, and the low 

 estimates which have been made thereof, to the fact that only one 

 substance having the formula C 4 H 7 X 3 has hitherto been recognised 

 by physiological chemists, and that therefore the properties of the 

 kreatinin obtained by Liebig's process from kreatin of flesh have been 

 supposed to be identical with those of the natural kreatinin of urine. 



I shall prove in Part II of this paper that the properties of the 

 kreatinins obtained from the kreatin of urinary kreatinin itself, by 

 treating it according to Liebig's direction, are in many respects 

 different from those of the natural base. It will be sufficient at 

 present to emphasise some of the differences in properties which I 

 have observed between the natural kreatinin of urine and the 

 kreatinin described by Liebig. 



1st. As regards reducing action. 



I have prepared kreatinin from flesh kreatin by Liebig's process, 

 vol. xliii. 2 o 



