SELECTED ARTICLES. 
ART, VI.— REMARKS ON SEVERAL OF THE FORMULA OF 
THE UNITED STATES PHARMACOPOEIA. By David Stew- 
art, Pharmaceutist, Baltimore. 
Since the last revision of the United States Pharmacopoeia, 
there has not, perhaps, occurred a theory which will have a 
more important influence in improving its formulae, than that 
of the application of the displacement process to the prepara- 
tions of tinctures, aqueous solutions, extracts, &c. I was 
first struck with its utility during the formation of a solution 
of opium, about two years since, in order to the preparation 
of morphia, — and, as the simple means used on this occasion 
may be substituted for the filter and screw press, in the sepa- 
ration of all the tincture from the dregs of opium in the pre- 
paration of tinct. opii, without the presence of that gelatinous 
precipitate which always accompanies the use of the latter, I 
will recommend it to those who wish to economise in this and 
other preparations. 
Bind together the long and short legs of two glass syphons 
with a narrow strip of flannel, at a point from which they 
will nearly reach to the bottom of the demijohn, or vessel 
containing the tincture — continue the operation until, upon 
the introduction of the tubes, the mouth will be obstructed by 
the flannel, — invert the demijohn and suffer the tincture to 
filter through the coil of flannel, until all of it has escaped ex- 
cept that which is retained by capillary attraction in the 
dregs. Then insert a small funnel into the long foot of the 
syphon, outside of the demijohn, and introduce into the demi- 
john a quantity of water sufficient to displace the remainder 
of the tincture. 
