196 



3. On a spontaneous Metamorphosis of Alloxan. 



I have found that alloxan forms two kinds of hydrated crystals. 

 Those, with six eqs. of water, are large, regular, transparent, and 

 do not readily effloresce in the air, nor undergo any change when kept. 

 But there is another form much more frequent, which, according to 

 my analysis, contains seven or possibly eight eqs. of water. It forms 

 large but irregular masses, with their sides graduated like steps, and 

 effloresces on exposure to the air very readily. I rather think this 

 kind forms in solutions which are slightly acid from free nitric acid, 

 which is likely to be the case in preparing alloxan. When placed in 

 stoppered bottles, and exposed to the natural changes of temperature 

 in summer, these crystals became partially liquified, and after a year 

 or two I found the contents of several bottles entirely changed. A 

 very large part had become nearly insoluble in cold water, and the 

 solution filtered from this part deposited, on evaporation, firsts small 

 colourless crystals; 5eco7i(i/y, a crystalline and yellowish mass; and, last 

 of all, the little remaining liquid dried up into a tough semi-crystalline 

 mass, which became pink on exposure to the air of the laboratory. 



I find the insoluble, or sparingly soluble matter, to be pure allox- 

 antine. The next crystals are quite distinct, both in form and pro- 

 perties, and the following portions exhibit also characters of their own. 

 No alloxan has appeared. But since the difference between alloxan 

 and alloxantine is simply that the latter contains one eq. of hydro- 

 gen more than the former, then the other substances must either 

 contain less hydrogen than alloxan, or, if the hydrogen has been de- 

 rived from water, they must contain more oxygen. I regard the latter 

 as the probable case, and I rather think that the new product or pro- 

 ducts are of an acid nature. But I have not yet been able to obtain 

 them pure ; and if I had, the difference in composition is so small, 

 that analysis will hardly suffice to make sure of it. We must there- 

 fore have recourse to the difference of properties, and here all that 

 I have as yet been able to do is to ascertain that besides alloxantine, 

 at least one, but probably two substances have been formed, different 

 both from alloxan and from alloxantine, as well as from all the allied 

 compounds with which I am acquainted ; and that one if not hoth of 

 these are acid compounds. The investigation is one of very great 

 difficulty, from the tendency of all these compounds to be altered by 

 contact with other substances, or by heat, and from the great simi- 

 larity in the properties of many of them. 



