February 24, 1872.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
GS5 
VOLUMETRIC ANALYSIS.* 
BY W. GILMOUR. 
{Concluded from page 669.) 
Acetic Acid. —One of the next substances my attention 
was called to was acetic acid, in determining - its strength 
for the making of solution of acetate of ammonia and 
other preparations into which it enters. The results I 
have obtained were not much more satisfactory than in 
the former case, although there generally was a much 
closer approximation to the standard strength. 
I have said they were not much more satisfactory, for 
we must hear in mind two things—I might almost say 
three—in considering the strength of this substance : 
first, the many important compounds and preparations 
into which it enters, determining more or less their 
relative strengths ; second, the reduction of the strength 
of the Pharmacopoeia preparation so as to conform to 
that of the commercial acid ; and third, the easy adapta¬ 
bility of its strength to that of the standard, and we 
may also add its permanency, in contradistinction to the 
nature of such a substance as sulphurous acid, of which 
we have just been speaking. 
The following table will show the varying strengths 
in half-a-dozen different samples I have from time to 
time lately tried:— 
Acetic Acid. 
182 grs. acetic acid = 1000 divisions solution of soda 
= 33 per cent. HC 2 H 3 0 2 = 28 per cent. C 4 H 6 0 3 . 
Monouydride. Anhydrous. 
Sample 1 = 29 - 7 p. 
c. HC 2 H 3 0 2 = 
25-2 p 
'. c. C 4 H 6 0 3 . 
„ 2 = 30-36 
77 
25-76 
7 ? 
„ 3 = 31-68 
77 
26-88 
77 
„ 4 = 31-84 
77 
27-02 
77 
„ = 32-01 
77 
27-16 
77 
„ 6 = 38-61 
77 
32-76 
77 
It will he observed that Sample 
1 is 
about 10 per 
cent, below the standard strength, and betwixt Samples 
1 and 6 there is a difference of above 25 per cent. 
Looking thus at the results we get some little idea of 
their unsatisfactory nature, but which we are very apt 
to overlook or forget, taking any of them individually. 
The 3S - 61 per cent, may by itself be considered a par¬ 
donable offence, but taking it in conjunction with another 
acid, such as Sample 1, as much below the standard, the 
consequences are neither to be lightly estimated nor 
connived at. Especially is this apparent in such an 
important compound as Mindererus Spirit, where the 
difference of strength, if made from samples such as 
these, would vary in extent one-fourth less or more as 
the case might be. All the above acids answered mode¬ 
rately well to the different tests for impurities—fixed 
impurities, metallic ditto and foreign acids—sulphuric, 
sulphurous and hydrochloric, so that they were good in 
every respect saving the one of strength. 
Hydrocyanic Acid. —This, it will be at once granted, con¬ 
sidering the potency of the compound, its frequent use by 
medical men in prescriptions, its important therapeutical 
effects, and the general instability of its strength, is not al¬ 
together an unimportant or unfit subject for study to the 
pharmaceutist. I began by making a few experiments as to 
the storing of it in bulk, etc. which I cannot say brought 
out anything new on the subject, although they generally 
confirmed what is already known. For example, that 
storing it in bottles—small in preference—quite full, ob¬ 
scured, tightly stoppered and finally inverted, will keep 
it good an indefinite period ; that is to say, as long as 
the retail chemist under ordinary circumstances requires 
to keep it: but on the other hand, a larger bottle, not 
quite full (and the smaller the contents the more certain 
the reduction), will never be stable in strength, even 
under otherwise most favourable circumstances. 
All this was known before, but I further tried how 
* Read at the Meeting of the North British Branch of the 
Pharmaceutical Society, January 1st, 1872. 
much acid would be lost in a given time out of a given 
quantity taken from the ordinary dispensing bottle which 
had been opened only for dispensing purposes. I must 
confess I was somewhat struck with the results, more 
especially as this is a loss I have never seen estimated in 
a similar way that I am aware of, and I was consequently 
not prepared to find it so large. I found that in a 4-oz. 
bottle opened on an average once a day, and a quantity, 
ranging probably from a few drops to a dram, or probably 
more occasionally, taken from it, the loss in the course 
of a fortnight was nearly one-third per cent. For 
example, one quantity I had in, and which was certified 
to be B.P. strength, but which on examination I found 
was actually 2T4 per cent., under the above circumstance 
and in the above time was reduced in strength to T83, 
thus losing in that time - 31. 
I need not say that here every care was exercised in 
the keeping and dispensing of this sample, so that no 
undue loss might take place; and I therefore conclude 
that under less favourable circumstances, a higher tem¬ 
perature or a less accurately-fitting stopper, for example, 
the loss might even be considerably greater. I have 
always found, however, that under similar circum¬ 
stances to the foregoing the loss existed in nearly an equal 
ratio. My observations lead me to remark one or two 
other features in the use of this acid,, none of which can 
be said to be unimportant when we consider the substance 
with which we are dealing. One is the unsatisfactory 
nature of a mixture containing this acid, especially if 
the mixture be ordered in considerable quantity, and 
dependent on this acid to any extent for its therapeu¬ 
tical effects. There is no possibility, so far as I know 
and have tried, of getting an uniform result in strength, 
first in the dispensing of such a mixture, and second and 
more especially in its use after dispensing. In the first 
case there is all the probability, so far as my experience 
goes, of an acid in one respect or another not standard 
in stock, and even where there is of its not being the 
proper strength after it has been dispensed. For ex¬ 
ample, if this acid is added first to a mixture ordered in 
some quantity, and the other ingredients added to it , the 
strength is not the same as if it were immediately added 
before being corked. The evil, moreover, is all the 
' greater if the acid is put, say, into a 12-oz. or 16-oz. 
bottle, and is then filled up directly from the stock-bottle, 
say either of a simple infusion or plain water, as not un- 
frequently happens. The evil here is a double one, for 
there is not only the loss of acid, but there is also its 
escape into the stock-bottle, and in no inconsiderable 
quantity, as I have over and over again demonstrated. 
In the second instance, viz. in the use of such a mix¬ 
ture, there is scarcely a possibility that any two doses 
can be exactly alike in strength, as the very cork by 
which the bottle is closed, and the frequent opening of 
the bottle, effectually precludes the idea. 
Al l this may prepare us for a difference in the strength 
of samples received from manufacturers and wholesale 
dealers, but it most certainly does not excuse the fact of 
such a variation, or the necessary acceptance of it by 
the pharmaceutist. The following table shows the varia¬ 
tions in strength of several different acids I have from 
time to time lately examined :— 
17*0 grs. 
Hydrocyanic Acid. 
1000 divisions solution of nitrate of silver 
Titrate of silver = 270 grs. dilute acid = 2 p. c. HCN. 
Sample 1 
2 
3 
3 - 0 per cent. 
4*28 
4 
5 
6 
7 
8 
2 - 92 
4 - 60 
T07 
2 - 14 
1-83 
1-90 
77 
?7 
77 
77 
77 
77 
77 
Scheele’s strength. 
B. P. strength. 
The first four - of the foregoing samples were war- 
