200 



(Ber. d. D. cli. G. 18 p. 982) of the acid potassium salt of allan- 

 toxanic acid or, according to Biltz and Topp of the potassium salt 

 of oxaluric acid. For want of sufficient material this could not be 

 further elucidated. 



From this it mnj therefore be concluded that the substance obtained 

 by Grimaux and the synthetically prepared amido-oxalyl biuret may 

 be considered as identical. 



In order to obtain the so-called biuret reaction it seems to me 

 desirable to first add the highly diluted copper sulphate solution and 

 then a solution containing at most i57o of KOH. 



Biltz and Top? carry out this i-eaction in the reverse way so 

 that there is a possibility that the substance is already undergoing a 

 partial decomposition before the copper sulphate is added, thus inter- 

 fering with the biuret reaction. Moreover, they use a KOH solution 

 D. 1.3 which will cause a more rapid decomposition. I have, there- 

 fore, mutually compared the reaction obtained with biuret itself, 

 widi the amido-oxalylbiuret prepared by my process and with the 

 substance obtained by Grimaux and have also compared the colouring 

 with that of the "Code des couleurs" of Klincksieck and Valette. 



On adding the different reagents rapidly the violet-red colouring 

 596 was always obtained in all three cases even when the KOH 

 solution was added previous to the copper sulphate. In the latter 

 case, however, the colouring had changed after 5 minutes; with 

 amido-oxalylbiuret and KOH D. 1.1 to 566, with KOH D. 1.3 to 

 541; with Grimaux's substance and KOH D. 1.1 to 561, with KOH 

 D. 1.3 to 528 D, whereas in the tirst case (CuSO, first, KOH afterwards) 



with my own preparation as well as with that of Grimaux — 



a change took place, after 5 minutes, to 571 when using KOH D. 1.1 

 and to 564 with KOH D. 1.3. 



In conclusion I wish to call attention to the difference in results 

 obtained by Biltz and Topp in the reduction with hydrogen iodide. 

 With oxalyldiureid they obtained hydantoine, with Grimaux's substance 

 a compound of the empirical composition C4H5O3N3 of which they 

 have not been able to give a definite structure. However, it is not 

 impossible that they were dealing here with uramil which has the 

 same empirical composition, begins to decompose above 270° and 

 also forms so-called salts. If we attribute to Grimaux's substance 

 the formula of amido-oxalylbiuret the formation of uramil is explained 

 quite as readily as the formation of hydantoine from oxalyldiureid. 



