554- Dr. Gregory on the Preparation of Alloxan. 



temperature below a certain point. 2. The 'whole of the al- 

 loxan is reduced by sulphuretted hydrogen to the state of 

 alloxantine. 3. The alloxantine is reoxidized by nitric acid, 

 and thus reconverted into alloxan. I cannot admit that this 

 process is either more simple or more easy than my own. On 

 the contrary, as I obtain nine-tenths of the whole alloxan, or 

 90 parts from 100 of uric acid directly as alloxan, and pure, 

 in the first crystallizations, while Schlieper first converts all 

 his alloxan into alloxantine, and then reconverts the alloxan- 

 tine into alloxan ; and further, as I use no other reagent but 

 nitric acid in preparing these nine-tenths, the advantage of 

 simplicity and facility is entirely on my side. 



From 4 ounces of uric acid, Schlieper obtains by his own 

 process 2 ounces 7 drachms and 20 grains of alloxantine, 

 equivalent theoretically to 3 ounces and 7 drachms of alloxan, 

 or nearly 97 per cent. But in reconverting this alloxantine 

 into alloxan by nitric acid, it will be found impossible to ob- 

 tain, practically, the whole alloxan, since some of it must re- 

 main in the mother-liquid ; and moreover, in the process of 

 oxidation by heating with nitric acid some alloxan is very 

 likely to be converted into parabanic acid, and thus lost. 

 Judging from experience, I should not expect the 97 per cent, 

 of alloxan obtained in theory to yield, in crystals, more than 

 90 per cent. 



As far as productiveness, therefore, is concerned, I may 

 claim also a superiority for my method. It is true that it has 

 not succeeded so well in the hands of Schlieper, but this must 

 I think be attributed to accidental causes, and possibly to a 

 want of perfect familiarity with the method on the part of 

 Schlieper, who seems to be so good an operator, that I cannot 

 doubt that he would, after a little practice, obtain the same 

 results as I have always succeeded in obtaining. 



Finally, I beg to remind those who may wish to try my 

 process, that what Schlieper describes as a modification of my 

 process is the process itself, unmodified ; because the only 

 change introduced by Schlieper consists in the use of acid at 

 1*4 or 1'42 instead of 1*3 or 1*35, as erroneously recommended 

 in my original process. In point of fact, the acid which 1 

 have long used for the purpose has the sp. gr. 1*412, and for 

 this number 1*3 or 1*35 was accidentally substituted in writing 

 or printing my former notice. In common with all chemists 

 I am much indebted to M. Schlieper for pointing out this 

 oversight. 



