188 Dr. Gregory on the 



yielded results which I shall not detain the Society by re- 

 peating, as they agreed entirely with those of Liebig and 

 Wohler. 



3. Dialuric Acid. 



Liebig and Wohler failed to obtain this acid in a separate 

 form, owing doubtless to iheir being compelled to make their 

 experiments on very small quantities. I found that it is easily 

 obtained when the preceding salt is dissolved, with the aid of 

 heat, in an excess of diluted hydrochloric acid. The liquid 

 deposits on cooling a quantity of sparingly soluble crystals, 

 not unlike those of alloxantine, yet quite distinguishable from 

 them; these crystals are dialuric acid. They have a strong 

 acid reaction, and readily neutralize the alkaline bases, form- 

 ing, with ammonia, the preceding salt; with potash, a spa- 

 ringly soluble salt in hard crystals; and with baryta an inso- 

 luble or very slightly soluble powder. The latter salts are 

 formed when dialuric acid is added to solutions of the soluble 

 salts of potash and baryta, so that the affinities of the acid are 

 powerful. 



Dialuric acid is not however very permanent in its uncom- 

 bined form, that is to say, when dissolved in water. It gra- 

 dually passes into alloxantine when exposed to the air, oxy- 

 gen, no doubt, being absorbed. The change may be traced 

 in the colour of the precipitate produced by barytic water. 

 If it be white, the acid has not yet undergone a change ; but 

 if it be pale pink, reddish-purple, or violet, this indicates the 

 gradually increasing proportion of alloxantine. Even the 

 crystals of dialuric acid, when left in the liquid from which 

 they have been deposited for a day or two, are found to be 

 partially changed into alloxantine. 



I made several analyses, both of the acid itself and of its 

 compounds, with potash and baryta. The details shall appear 

 hereafter : at present I may state that these analyses corre- 

 spond to the hypothetical formula given by Liebig and Wohler, 

 namely C 8 N 2 H 4 O s = C 8 N 2 H 3 7 + HO, in which HO 

 seems to be capable of replacement by MO in the salts. It is 

 important to observe that urile or urilic acid, C 8 N 2 4 + H 4 

 4 , = 4< atoms of water, contains the elements of dialuric acid. 



It is proper to state that Liebig and Wohler did obtain by 

 the same process as I adopted the crystals of dialuric acid, 

 which, however, appear to have been partially converted into 

 alloxantine before they were examined*. Indeed my experi- 

 ments lead me to believe that the substance described by these 

 chemists as dimorphous alloxantine is nothing but dialuric 

 acid, more or less completely converted into alloxantine, and 

 * Ann. der Pharm., xxyj, 280. 



