232 
ON SOCOTRINE ALOE JUICE. 
when the liquid becomes cold it retains its transparency and does 
not deposit any crystals. By evaporation the juice yields a solid, 
transparent extract, having all the characters of fine Socotrine 
aloes, in which no traces of crystalline texture can be discovered. 
Mr. Jacob Bell has ascertained that 141bs. of the juice yield 81bs. 
12ozs. of solid extract, or 62i per cent. When the juice is 
mixed with cold distilled water? it becomes opaque yellow, and 
renders the water turbid, but is not miscible with it. If, how- 
ever, heat be applied, the juice dissolves in the water, forming 
an almost clear, rich red liquid. As the solution cools, it at 
first becomes turbid owing to the separation of an opaque yellow 
precipitate, which, apparently, is the crystalline principle in an 
amorphous form. This gradually separates from the liquid and 
collects as a clear resiniform mass (commonly called the resin 
of aloes) at the bottom of the vessel, leaving the supernatant 
liquid tolerably clear. If the juice be shaken up with rectified 
spirit of wine an uniform clear mixture is obtained, from which 
numerous yellow crystals rapidly fall to the bottom of the liquid. 
Similar results are obtained when we mix the juice with equal 
parts of rectified spirit of wine and water. 
This crystalline constituent of Socotrine aloes is doubtless, 
either the aloin* described by Messrs. T. & H. Smith, of Edin- 
burgh, and by Dr. Stenhouse, or a principle closely allied to it. 
Dr. Stenhouse, to whom I have given a sample of it, is now en- 
gaged in its investigation ; and in a letter which I have received 
from him, he says, that though he has not been able to get the 
aloin ready for analysis, yet, from the experiments he has already 
made with it, he has scarcely a doubt that it will be found iden- 
tical with that formerly obtained from Barbados aloes. It forms, 
he adds, a precisely similar combination with bromine, and, in 
short, agrees with it in every particular ; I shall, therefore, pro- 
visionally term this crystalline principle the aloin of Socotrine 
aloes. On comparing it with a fine specimen of aloin kindly 
presented to me by Messrs. Smith, I find its crystals smaller and 
more tapering — the summits of the crystals being more acute. 
In drying, the crystals of the Socotrine aloin have a strong 
tendency to break up ; so that crystals which in the moist state 
*See American Jour. Pharm. vol. xxiii. page 238. 
