ON ALOES AND ALOETINE. 
49 
this operation, the sulphuret of lead was covered by a perfectly- 
colourless supernatant liquor, which, on being carefully decant- 
ed and evaporated in vacuo, afforded no crystals, but dried in 
scales, having the appearance of a kind of varnish, with a very 
slight tint of yellow, 
I used the product thus obtained in my examination for the 
presence of nitrogen, and also in the analysis with oxide o 
copper. To distinguish it from the crude aloes I have called 
it aloetine. 
Aloetine is obtained in the form of nearly colourless scales, 
if in the process air be as much as possible excluded. It is 
very soluble in water and in alcohol, little soluble in ether, and 
completely insoluble in the fixed and essential oils. On cal- 
cination in close vessels, a shining voluminous residue is left, 
which entirely disappears on incineration in the air. The 
aloetine is not coloured by either the per or proto salts of iron; 
and it gives no precipitate with acetate of lead; in other re- 
spects its reactions are similar to those of socotrine aloes. 
If the aloetine be dried in contact with air, the scales, in- 
stead of being colourless, will have an intense red colour, due 
to a slight absorption of oxygen. With the exception of the 
difference in colour, it undergoes no modification in its chemi- 
cal properties, and probably analysis would hardly detect any 
difference between that altered by the contact of air, and that 
prepared in vacuo. The process may therefore be rendered 
much more easy by drying the product over a water-bath, or 
by exposure to the heat of the sun, when it is not desired to 
obtain the aloetine in a state of absolute purity. 
Aloel ine possesses in a high degree the purgative properties 
and bitter taste of ordinary aloes. For medicinal use eight 
parts of aloetine are equivalent to ten parts of socotrine aloes 
and fifty parts of Cape aloes. — lb. from Jour, de Pharm. 
VOL, XIII. — NO. i. 
5 
