October 7, 1871.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS 
209 
fempnime* 
* . * 
No notice can be taken of anonymous communica¬ 
tions. Whatever is intended for insertion must be authenti¬ 
cated by the name and address of the writer ; not necessarily 
for publication , but as a guarantee of good faith . 
Tincture Tresses. 
Sir,—About this time last year, I published in the columns 
of your Journal (Piiarm. Journ. 1870, p. 321) a table of re¬ 
sults which had been obtained when hydraulic pressure was 
used, for the recovery of spirit from the marcs of the various 
tinctures of the British Pharmacopoeia. 
At that time some of your correspondents thought the 
matter worthy of further attention ; and from several phar¬ 
macists, who had compared my results with those they had 
been in the habit of obtaining with the ordinary tincture 
press, I received inquiries. The question most frequently 
asked was, “What would be the cost of a small hydraulic 
press that could be used for the removal of the spirit from 
the marc of about one or two gallons of tincture ? ” 
Upon making inquiry, I found that not only were the 
smallest presses that hydraulic engineers were accustomed to 
make, much too large for a small pharmaceutical laboratory, 
but that the cost was so excessive, as compared with that of 
the usual press, that the extra outlay would not have repaid 
the purchaser, even if he could have recovered an additional 
ten per cent, of alcohol, over and above the quantity that he 
had been in the habit of obtaining, with the ordinary screw 
press. 
The editorial reference in your issue of September 16th to 
hydraulic tincture presses again brings the subject before 
us; and I, for one, am anxiously looking forward to the 
description of the press you have promised to place before 
the readers of the J ournal. 
In the meantime, I think we cannot be better occupied 
than by making ourselves thoroughly acquainted with the 
power and merits of our old friend the screw tincture press. 
This done, we shall be in a better position to judge of the 
qualities of the improved machine that you purpose de¬ 
scribing. 
I here allude to the power more especially, because I 
think that very exaggerated notions are formed of the capa¬ 
bilities of the ordinary laboratory tincture press. For in¬ 
stance, we were recently told by Mr. Staples (who, by the way, 
is a pattern to us in the manner in which he applies his en¬ 
gineering skill to pharmaceutical requirements), at the British 
Pharmaceutical Conference at Edinburgh (Piiarm. Journ. 
Sept. 9, 211), that the pressure obtained in the tincture 
press, as ordinarily met with, was nearly twenty tons. Now, 
without making any remarks upon the merits of the press as 
designed by Mr. Staples, an illustration of which appeared 
in your Journal, and upon which one of your correspondents 
has since commented, I should like, with your permission, to 
bring forward facts in support of the statement I have made, 
and I will do so by the following illustrations. (Before, how¬ 
ever, doing so, it will be only just to say that Mr. Staples 
remarks in his communication “it maybe objected that these 
figures are somewhat theoretical)”:—I have in use two 
presses; the one (a) is rather old-fashioned, but very strongly 
made, and of a capacity of one gallon ; such an one, I imagine, 
would be found in many a country pharmacy; the other (£>) 
is one of more recent date, of about the same size (Lynch and 
Co., Aldersgate Street, E.C., makers). The mechanical ad 
vantages in the use of either of these can easily be deduced 
from the following; as the circumference of the circle de¬ 
scribed by the lever tcliere the poiver acts is to the pitch of the 
screw, so is the force applied to the resistance :— 
(a) Lever 10 inches. 
Pitch of screw -fy inch (-312). 
Force applied at extremity of lever 50 lb. 
10x2x3-1416x50 
Then--=10532 lb. 
or about 4£ tons (theoretically). 
( b ) Lever 8 5 inches. 
Pitch of screw £ inch (’25) 
Force applied at extremity of lever 50 lb. (theoreti- 
-is 1416 * 5 =10081 lb. CalW 
or about 4j tons. 
In these calculations it will be seen that the amount of 
force applied to the end of the lever is only half that upon 
which Mr. Staples has based his calculations. The lever, 
too, in both presses is somewhat shorter, while the pitch of 
the screw is materially larger in both, in one case being 
nearly twice the size. Now as I have ascertained that these 
measures given, accurately represent the various dimensions of 
the tincture presses of trade, which can be verified by a visit 
to any druggists’ sundriesman’s store in this city, it re¬ 
mains for me to give a reason, why I prefer to take 50 
pounds as the force applied at the extremity of the lever 
rather than 100 pounds. 
Upon reference to a work by Professor Rankine, I found 
that the average force applied by a man at the end of a lever, 
in such a position as met with in the tincture press (he in¬ 
stances pulling an oar), was 26 - 5 lb., and while working a 
crank 20 lb. It cannot, therefore, be said that in nearly 
doubling this amount, as I have done, my calculation has been 
taken upon a minimum power, but rather in excess of the true 
maximum one. 
A little reflection will show, that the power exerted by a 
man in the position required for the motion of the tincture 
press lever is very different to the raising of a weight from 
the ground, in which additional muscles are brought into 
play. 
It must always be remembered that when the screw is 
loaded, the friction to be overcome is something considerable; 
and for this reason, I have termed the results obtained by 
the above calculations as theoretical; for in order to obtain 
an exact idea of the real pressure exerted, a deduction of at 
least 30 per cent, must be made from the calculated pressure. 
I think, therefore, that if the power obtained in the ordi¬ 
nary 1 gallon screw tincture press be computed to be two 
tons (as a maximum), a more accurate idea vill be given 
of its power than when twenty tons is name ! as the total 
force obtained. 
Charles Umney. 
Laboratory, 40, Aldersgate Street, JE.C. 
The Chippenham Case. 
Sir,—I cannot think that your correspondent M. P. S. al¬ 
together deserves the indignation with which Dr. Fox has 
visited him. 
lie at all events is justified in considering a solution of 
eighty grains to the ounce of corrosive sublimate as at the 
least a very strong application to the head of a child, and his 
argument is scarcely unfair when he objects to it because it 
is both “ both powerful and caustic.” 
Here, as it seems to me, he has touched on the real source 
of risk attending its use ; corrosive sublimate is not only one 
of the most powerful in its effects on the system of the com¬ 
pounds of mercury, but it is also one of the most corrosive. 
We know what a valuable protection our epidermis or 
scarf-skin is to us in preventing the contact of various poi¬ 
sonous substances with the underlying true skin, which is 
otherwise so readily capable of absorbing all kinds of noxious 
substances into our systems. And we may presume that 
when we increase the strength of a lotion of corrosive subli¬ 
mate to a point at which it exercises a corrosive action on 
the epidermis, we not only augment the quantity of soluble 
poison that is brought into such close proximity to the true 
or absorbent skin, but we also run a risk of destroying the 
thin protection which is the only obstacle to its absorption. 
When, moreover, we reflect that so strong an application as 
the one in question can scarcely ever fail to raise a blister, 
and consider the fair possibilitj' of that blister getting broken, 
we must admit that a timid man might be excused for hesi¬ 
tating before he applied it. 
If, then, there be any possibility, however remote, of the 
lotion being absorbed by the skin, it may be well to consider 
what is the quantity of corrosive sublimate that incurs this pos¬ 
sibility at each ordinary application of the lotion. Eighty 
grains to the ounce gives ten grains to the drachm. Now, 
placing an average adult dose of corrosive sublimate at the 
sixteenth of a grain, the drachm of lotion will be found to 
contain one hundred and sixty adult doses. Suppose, how¬ 
ever, that only one-fourth of that quantity (viz. fifteen drops) 
gets applied at a time, then we still get forty adult doses con¬ 
tained in a single application to the head of a child. 
Now since in ringworm there are usually several patches, 
and some of them often attain a considerable size, 1 should 
be disposed to say that fifteen drops is a moderate rather 
