Dr. Gregory on the Preparation of Alloxan. 553 



acid the whole of the uric acid that is to be dissolved before 

 collecting the alloxan: 



Let us now consider the productiveness of this method. I 

 have already stated my average of former results to have been 

 90 per cent, of crystallized alloxan, exclusive of the mother- 

 liquid, which corresponded to one-tenth more. As the pro- 

 cess now stands we have — 1. The first crop of crystals of al- 

 loxan, varying with the proportion of water used to dissolve 

 the anhydrous alloxan. 2. The second crop of the same cry- 

 stals. 3. The alloxantine from the mother-liquid converted 

 into alloxan, or calculated in that form. I take no account 

 of the parabanic acid. 



Experiment 1. — Uric acid 2600 grains ; alloxan, first crop, 

 1950 grains, second crop, 550 grains ; alloxantine, 200 grains, 

 equivalent to alloxan, 290 grains. In all, therefore, from 2600 

 grains of uric acid, 2790 grains of hydrated alloxan, or 107 

 per cent, nearly. 



Experiment 2. — Uric acid, 11 30 grains; alloxan, first crop, 

 800 grains, second crop, 140 grains; alloxantine, 80 grains, 

 equivalent to alloxan, 116 grains. In all, therefore, 1056grs. 

 of alloxan from 1 1 30 of uric acid, or 93 per cent. 



Experiment 3. — Uric acid, 1500 grains ; alloxan, first crop, 

 1150 grains, second crop, 270 grains; alloxantine, 120 grains, 

 equivalent to alloxan, 174 grains. In all, therefore, from 

 1500 grains of uric acid, 1594 grains of alloxan, or 106 per 

 cent. 



The above results, averaging 102 per cent, of pure hydrated 

 alloxan, were obtained without difficulty. Indeed the only 

 delicate point in the process is the attention necessary to avoid 

 too great a rise in temperature, alloxan being decomposed by 

 heat even when simply dissolved in water, but still more when 

 acid is present. A little experience however makes this quite 

 easy ; and besides, this difficulty attaches equally to Schlieper's 

 new method, as we shall see. 



The formula of uric acid being Ci N 4 H 4 Og, while that 

 of hydrated alloxan is C 8 N 2 H 4 O 10 -f6 aq, it is obvious that 

 100 parts of uric acid can produce about 128 of alloxan. It 

 is not likely that we shall ever obtain the full proportion with- 

 out loss, but I consider my process, simple as it is, to furnish 

 a very satisfactory approximation, considering the impossibi- 

 lity of separating the whole alloxan from the acid liquid in 

 which it is formed. 



If we now refer to Schlieper's account of his new method, 



we find that it includes the following operations: — 1. The 



uric acid is acted on by hydrochloric acid and chlorate of 



potash, care being necessary, as in my process, to keep the 



Phil. Mag. S. 3. No. 190. Suppl. Vol. 28. 2 P 



