RESEARCHES ON ALOETINE. 
543 
I then dissolved a similar quantity of Barbadoes aloes in 
boiling water, and evaporated the solution to dryness, on a 
sand bath, in the open air. It became transparent and 
vitreous, that is to say, quite similar to Socotrine aloes ; but, 
as soon as this transformation was accomplished, it was 
impossible to extract the small trace of crystals from it. 
The mystery was then cleared up, and I arrived at the con- 
viction that — 
1. All the kinds of juices of vitreous and transparent aloes 
(Socotrine aloes, Cape aloes, &c.) have undergone the action 
of heat, and their crystallizable principle is metamorphosed 
into an amorphous substance, which is ordinarily called 
resin of aloes, but which is no other than aloetine, which has 
become, by molecular change, amorphous aloetine, insoluble 
in water. 
2. All the kinds of opaque aloes with a waxy fracture were 
obtained by desiccation in the open air, and without the aid 
of heat ; they all contain crystallizable aloetine. 
Messrs. Smith’s process of preparation is very simple in 
principle, but, in practice, it is troublesome to evaporate, in 
vacuo , large quantities of liquid, and, moreover, the yield is 
very trifling. I endeavoured, therefore, to overcome this 
difficulty, and, after some failures, I arrived at the following 
method, which gives about 15. per cent, of product. 
Preparation of Aloetine . — Distilled water is boiled for an hour, 
in order to expel the air, and, when cold, 2 kilogrammes 
are poured on 1 kilogramme of Barbadoes aloes in powder, 
which is kept ready in a dish. By agitating rapidly, the 
solution is effected in a few minutes ; the dish is covered as 
accurately as possible, and left to repose for about a quarter 
of an hour. The liquor must be decanted into a conserve 
glass, of such a size as to exactly contain it ; a little ether is 
poured in, in order to expel the air as much as possible, and 
to prevent mouldiness ; the lid is immediately fitted on, and 
carefully luted. It only remains to place this vessel in a cool 
situation, and to leave it to itself for a month. It is then 
opened, and, after having separated all the portion still re- 
maining liquid, we find its interior lined with a compact mass, 
and, as it were, covered with stalagmites. These concretions 
are no other than a mixture of amorphous aloetine, foreign 
earthy matters, and crystallizable aloetine. 
Now, as the latter is very sparingly soluble in cold water, 
and much heavier than the impurities which accompany it, 
it is easy to separate it, mechanically, by simple levigation. 
The crude aloetine is under the form of yellowish and 
radiated crystalline grains, giving way between the teeth, like 
