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 thmk this 

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

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

 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 larae part had become nearly insoluble in cold water, and the 

 solution filtered from this part deposited, on evaporation, first,. mzXi 

 colourlesscrystals;..conrfZy,acrystalline andyellowish mass; and, ast 



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

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



I find the insoluble, or sparingly soluble matter, to bepureallox- 

 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 

 rontain less hydrogen than alloxan, or, if the hydrogen has b^en 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 obta n 

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

 hi 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 a loxa.tme 



at least one, but probably two -^^^ ^^ ^'^-f -";^; f^ 

 hoth from alloxan and from alloxantine, as well as from all U.e alhed 

 compounds with which I am acquainted ; and that one if not both o 

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

 c^ffi culty, from tlJtendency of all these compounds to be alt.-ed by 

 contact iith other substances, or by heat, and from the great sum- 

 larity in the properties of many of them. 



