PHARMACEUTICAL NOTICES. 
103 
Displacement of Senna. 
Some of my colleagues have mentioned to me a difficulty 
they encountered in preparing the Fluid Extract of Senna, 
agreeably to the directions submitted by me in the 4th No. of 
the last volume of this Journal. 
By reason of the large proportion of water composing the 
menstruum, the organic tissues become swollen and impene- 
trable, from the developement of the albuminous matters 
which cover them, and the mass assumes a pasty consistence, 
especially if the Senna is in a finely divided state, which ren- 
ders percolation slow and difficult, if it does not entirely 
cease. 
As this same difficulty has since presented itself to my 
own observation, I naturally sought a remedy. I was unwilling 
to employ a large proportion of alcohol, from the necessity of 
either losing it, or the trouble of recovering it by distillation; 
neither was I willing to employ decoction, as it would require 
a larger quantity of water, and my preparation would be ex- 
posed to the injurious consequences attending long evapora- 
tion. I therefore resorted, after maceration, to mechanical 
pressure, which in depriving the Senna of its fluid parts, car- 
ried away nearly the whole of the mucilage. 
The Senna after this was transferred to the displacement 
apparatus, and being treated with the remaining menstruum, 
no longer occasioned any difficulty. 
The quantity of alcohol, however, in the formula might be 
increased without any disadvantage, as also the oil of 
fennel. 
Facts connected with the Detection of Arsenic, 
Some time ago I prepared for the use of the readers of this 
Journal, a paper upon the detection of Arsenic, compiled from 
the best authorities, and in which were summed up all the 
latest improvements made in Toxicological Chemistry. Of 
late, more than ordinary attention has been given to this 
branch in England and France, particularly the latter. So 
