1887.] 



Mr. G. S. Johnson. On Kreatinins. 



365 



VIII. " On Kreatinins. I. On the Kreatinin of Urine, as distin- 

 guished from that obtained from Flesh-kreatin. II. On the 

 Kreatinins derived from the Dehydration of Urinary 

 Kreatin." By George Stillingfleet Johnson, M.R.C.S., 

 F.C.S., F.I.C. Communicated by George Johnson, M.D., 

 F.R.S. Received May 5, 1887. 



(Abstract.) 



Paet I, 



This investigation was suggested by a careful study of the reducing 

 action of normal human urine upon picric acid in presence of potash 

 at the boiling temperature. 



The picric acid method for the quantitative estimation of sugar in 

 urine was introduced by Dr. George Johnson in 1883. Whilst 

 assisting him in working out the details of the process, the author's 

 attention was drawn to the small amount of reduction exerted by all 

 specimens of normal human urine. The average picric reduction 

 observed was equal to that which would be effected by a solution of 

 glucose containing 0"6 grain to 1 fluid ounce. 



The reduction of cupric oxide in boiling alkaline solution was 

 always somewhat greater, averaging 0*7 grain per 1 fluid ounce. 

 Although many physiological chemists express the opinion that 

 normal human urine contains always a little sugar, to which this 

 reducing action is to be attributed, the author's researches have led 

 him to an opposite conclusion. 



The reducing agent of normal urine differs from glucose in pro- 

 ducing some reduction of picric acid in presence of potassium hydrate 

 at the ordinary temperature (vide Dr. R>. Kirk, ' Lancet,' June 16, 

 1883). 



The reducing agent of normal urine cannot be made to undergo 

 the alcoholic fermentation in presence of yeast. Nevertheless, 

 Dr. Pavy (' Med. Chir. Soc. Trans.,' vol. 63, p. 222) attributes one- 

 fourth of the reducing action of normal urine upon cupric oxide to 

 uric acid, and the remaining three-fourths to " the small amount of 

 sugar naturally present in urine." 



Briicke is also of opinion that normal human urine contains a 

 small quantity of sugar. 



Uric acid and kreatinin together are credited by Prof. E. Salkowski 

 (* Centralblatt fur die Medicinischen Wissenschaften,' March, lb86) 

 with from one-sixth to one-fifth of the total reducing action of normal 

 urine, the remainder being due to ''other substances, and very 

 probably to compounds of glycuronic acid (Glykuronsaureverbind- 

 ungen)." 



