508 
IS CHLORODYNE SUBJECT TO A MEDICINE STAMP ? 
column of liquid has only been the result and the measure of the existence of that 
partial vacuum. The column produced and maintained by the agency of a force superior 
to its own density, exerts no inherent potentiality,—the liquid which drops into it at 
the top drops out of it at the bottom, in virtue of the gravity of those dropping portions 
themselves; the column itself remains one of the walls, so to speak, of the apparatus, 
helping to maintain the vacuity, and differing only from the other portions of its walls 
in being permeable by the liquid dropping into it. And if, as I have asserted, the rate 
of dropping through the stopcock increases in some relation to the height of the column, 
that increase must be clearly due, not to the column, the liquid wall of the instrument, 
any more than to its solid walls, but to the differential atmospheric pressure brought 
about by the arrangement. 
.This instrument, therefore, I designate a contrivance to illustrate the operation of 
aerostatic force, and, as far as I can see, no other force is immediately concerned in the 
experiment we are supposed to have made with it. 
And my filter lesembles it exactly in all that concerns the principles of its action. 
The di opping apertures are many, instead of single; and I get rid of the air from within 
by simply filling the apparatus with liquid at once, instead of employing the aid of a 
pump. The external pressure, whatever its amount, we have seen to operate over every 
portion of the instrument alike. It signifies nothing, therefore, how many dropping 
apertures my filtering-medium may possess, provided the orifice of the delivery-tube be 
sufficiently large to allow freely the escape of all the liquid passing through them,—and 
t le column being, as I have stated, the measure ” of the vacuity, and consequently of 
the power evoked, the pressure upon the upper surface of the medium will be equal to 
the weight of the under column multiplied by the number of times the area of the 
medium exceeds the area of the column. 
It is this great amount of force which (I think by simple means) I have succeeded in 
bringing to ‘ aid filtration.” 
I must just add a few words upon the quantitative results of the employment of this 
force. You will remember the law of Torricelli, as interpreted or enlarged by Dr. Att- 
ffeld, declared the rate of flow of liquids from apertures to be in proportion to the square 
i°! ^? e P owers 0 P er ating. According to this law, the rate of flow from my filter 
should be in proportion to the square root of the length of the column. Now the actual 
rate, as above quoted, shows a greater increase than that law would justify: but, I think, 
when we remember the amount of statical force evoked, and bear in mind that the 
medium consisted of material to some extent expansible, the excess may be fairly attri¬ 
buted to the very probable enlargement of the pores of the medium under the influence 
ot the pressure. Had we employed a medium of absolutely rigid material, and experi¬ 
mented with perfectly pure water, I do not believe this apparent difficulty would have 
appeared. 
I wish to state, in reply to some inquiries that have been addressed to me, that I do 
not manufacture or sell the instrument, but simply suggest it for the consideration of 
my fellow-pharmaceutists. 
ORIGINAL AND EXTRACTED ARTICLES. 
IS CHLORODYNE SUBJECT TO A MEDICINE STAMP? 
TO THE EDITORS OF THE PHARMACEUTICAL JOURNAL. 
Gentlemen, I beg to hand, for publication, the subjoined correspondence for 
geneial information to the trade; it is relative to a public announcement by 
i h. l. Darling, of Weymouth, stating that he had received an intimation from 
the Inland Revenue Office, that the Chlorodyne sold by him was not liable to 
the patent medicine duty. 
I applied for this information that I might be able to give a reply to several 
communications I had received on the subject. 
I he decision of the Commissioners of Inland Revenue is quite conclusive, that 
