DECOCTUM ALOES COMPOSITUM. 
335 
The principal cause of the deposition of so much 'of the 
aloes, when the decoction has been kept for some time, may 
be traced, we believe, to the action of the heat during its pre- 
paration. A large proportion of the aloes and of the myrrh 
is soluble in solution of carbonate of potassa, even without 
the aid of heat, the insoluble parts being, according to some 
eminent authorities, more highly oxidized in their constitu- 
tion, and more irritating in their effects, than those that are 
dissolved by this menstruum. By the continued application 
of heat, a change is effected in the soluble constituents, which 
are thus rendered to a certain extent insoluble, while the mu- 
cilage of the myrrh, together with the extract of liquorice, 
tend to prevent the immediate deposition of the insoluble par- 
ticles: a portion of the volatile oil of the saffron is also driven 
off during the boiling. 
Thus upon the care bestowed in preparing it — upon the 
degree of heat applied in the boiling, will in a great measure, 
depend the constitution and the effect of the medicine; and as 
it is impossible, according to the instructions of the college, 
to define or to regulate exactly the heat applied, it follows as 
a necessary consequence, that decoction of aloes made accord- 
ing to the Pharmacopeia, is seldom met with twice alike. 
A preparation possessing-, we believe, all the properties of 
that designed by the college, and not subject to the same va- 
riations, may be obtained by making an infusion instead of a 
decoction, and, we trust, the college in a future edition of 
their Pharmacopeia will consider the propriety of making 
this alteration in the formula: it would be in strict accord- 
ance with the mode of proceeding directed in another case 
namely, that of the purified extract of aloes, in which the 
aloes is ordered to be macerated with the water at a gentle 
heat for three days, and the clear liquor decanted from the 
dregs. Lond. Pharm, Journ. and Trans. 
