282 ON ALOINE, THE CATHARTIC PRINCIPLE OF THE ALOES. 
picric acids. There appears, therefore, great reason to believe 
that all the three kinds of aloes contain aloine. 
Since the above was written, I have learned from Mr. Smith 
that he has not succeeded in obtaining crystallized aloine from 
either Cape or Socotrine aloes. Mr. Smith does not doubt that 
both of these species of aloes also contain aloine, though most 
probably contaminated with so much resin, or some other sub- 
stances, as prevents it from crystallyzing. What tends to con- 
firm Mr. Smith in this opinion is, the observation he has made, 
that, when the crude crystals of aloine are allowed to remain in 
contact with the mother-liquor of the Barbadoes aloes, they dis- 
appear and become uncrystallizable. I have also observed a 
similar occurrence in the mother-liquors of tolerably pure aloine. 
These become always darker and darker ; so that if we continue 
to dissolve new quantities of aloine in them, at length scarcely 
any of it crystallizes out, and the whole becomes changed into 
a dark-coloured magma. 
In the year 1846, M. E. Robiquet published an account of 
an examination he had made of Socotrine aloes. By treating 
the concentrated aqueous solution of this species of aloes with 
basic acetate of lead, he obtained a brownish yellow precipi- 
tate, which was collected on a filter and washed with hot water. 
On decomposing this lead compound with sulphretted hydrogen 
and evaporating the solution to dryness, he obtained an almost 
colourless varnish, consisting of a scaly mass, which was not in 
the least degree crystalline. M. Robiquet subjected this sub- 
stance, which he called aloetine, to analysis, and obtained the 
following result : — 
per cent. 
8 C = 27*7 
14 H = 10-8 
10 O = 61*5 
1000 
It is plain, therefore, that M. E. Robiquet’s aloetine, if it really 
is a definite organic principle, which I very much question, is 
certainly a very different substance from the aloine which has 
formed the subject of the present notice. 
London, Edinb. and Dublin Philosophy Mag. 1850. 
