FURTHER STUDIES ON UREIXE. 531 



St.-Pétersbourg, Tome XIII, As 5): «On the other handitisa mostiuteresting 

 fact, that the j)recipitates of Urea Oxalate also retain a considérable amount of 

 deoxidizing substances». 



«It was my intention to make nse of the copions précipitâtes of Urea 

 Oxalate for laboratory piirposc^s and to prépare from them pure urca. I 

 treated the precipitate with liniewater (Kalkmilch), purified the browu liquid 

 with animal charcoal, heated the wholc to ebullition, evaporated to dryness 

 and treated the remaining charcoal powder with alcohol. After evaporating 

 the alcohol there remained iirea in the shape of yellowish crystals; these 

 crystals deoxidized a cold solution of KMnO^, whereas the pure urea does 

 not possess tliis capacity». 



Tliis phenomenon cau be easily understood, when we consider that 

 ureine combines with oxalic acid; the precipitate which Dr. Kuliabko con- 

 sidered to be Urea Oxalate was in reality a Compound of Urea Oxalate and 

 of Ureine Oxalate, and the yellow crystals obtained were simply urea to- 

 gether with ureine or a derivate of ureine. 



As to Liebig's method of determiuing the percentage of urea by Mer- 

 cury Nitrate, this latter cannot be used for such a purpose/or Mercury Ni- 

 trate combines just as well with ureine as it does with urea. 



In fact, Liebig's method has given us the percentage of ureine -t- 

 urea, of which percentage only Vg or even only ^4 belongs to urea, while ^ ^ 

 or even ^4 beloug to ureine; in diabctic urines this différence in proportion 

 betweeu urea and ureine is still more strikiug, for I have found diabetic 

 urines coutaining 20 — 30 times more ureine than urea, the latter being 

 présent in quantities of only 0,15 — 0,5%, whereas the percentage of ureine 

 reached 6 — 8^0 ^nd even more! This seems incredible, but will iradoubt- 

 edly be confirraed by compétent investigators. 



In spite of the similarity between reactions of ureine and of urea, it is 

 easy to distinguish the one from the other. Ureine gives a blue color with 

 a solution of Potassium-Ferri-Cyanate (red prussiate of potash) and Ferrum 

 Perchloridura, while urea is indifferent to this color -reaction. With Feh- 

 lin g's solution it gives a brown-red color, but no brick-precipitate. 



Ureine is an energetic deoxidizor of the Permangauates. whereas urea 

 is not affected by them; % of the reducing and deoxidizing force of the 

 human urine is caused by ureiue. This capacity of deoxidizing Potassium 

 Permanganate enables us to détermine accurately in what quantities ureine 

 is présent in the human urine. Repeated and careful tests have shown me 

 that 1,5 gr. ureine deoxidize exactly 1,0 gr. KoMn^O^ in 24 hours. (1,5 gr. 

 ureine deoxidize 1,4 Potassium Permanganate in the course of 4 — öAveeks). 

 Bearing theu in mind that 1,0 gr. Permanganate is decomposed within 24 



ФиЕ.-Мат. стр. 13S. 5 



