234 
ON SOCOTRINE ALOE JUICE. 
as in hepatic aloes, is dark brown. On submitting this dark 
brown insoluble portion to microscopic examination, I find that 
it contains depolarizing crystals. 
Artificial Socotrine aloes (prepared by evaporating this aloe 
juice) also yields, when digested in rectified spirit, a dark brown 
insoluble portion. 
I think, therefore, that Socotrine aloes differs from hepatic 
aloes in the circumstance of its having been prepared by the aid 
of artificial heat; by which its aloin constituent has become al- 
tered. This inference is furthered substantiated by the fact, that 
after it has been melted, hepatic aloes is found to have acquired 
the clearness and transparency of the Socotrine sort. 
The clear supernatant portion of aloe juice, from which the 
above crystals have subsided, would probably also yield, by spon- 
taneous evaporation, an extract resembling, or identical with, 
Socotrine aloes. 
That Socotrine and hepatic aloes were obtained from the same 
plant, and were not different species of aloes, I have long sus- 
pected ; and in the first edition of my work on Materia Medica, 
published in 1840, I have observed that "the similarity of the 
odor of Socotrine and hepatic aloes leads to the suspicion that 
they are obtained from the same plant ; and which is further 
confirmed by the two being sometimes brought over intermixed, 
the Socotrine occasionally forming a vein in a cask of the hepatic 
aloes. " 
This intermixture of the two sorts of aloes in the same cask 
might be explained by supposing that the consolidation of the 
clear portion of the juice has produced the so-called Socotrine 
aloes; while the opaque aloin-containing portion of juice has 
yielded what is termed hepatic aloes. 
In the third edition of my work above alluded to, I have stated 
that the name of opaque liver-colored Socotrine aloes might with 
propriety be applied to hepatic aloes. But until the present 
time I have been unable to offer a plausible explanation of the 
cause of the difference in these two commercial kinds of aloes. 
Prom the preceding remarks I think we may infer : 
1. That aloin pre-exists in a crystalline form in the juice of 
Socotrine aloes. 
2. That the substance which deposits as a decoction of Soco- 
