ON THE ACETIC ACIDS OF THE THREE PHARMACOPOEIAS. 299 
taken to secure its perfect purity and uniformity of strength, made its way all 
over the country, because it was convenient and economical, and afforded a 
pure flavoured result very different to the varying samples of the more legiti¬ 
mate “ distilled vinegar” of the Pharmacopoeia ; and I very well recollect in my 
early days it was used somewhat clandestinely in all preparations in which dis¬ 
tilled vinegar was ordered. Thus it is clear that the strength of distilled vine¬ 
gar was generally understood to contain about three per cent, of real acid. When, 
however, the Pharmacopoeia of 1824 made its appearance with its acid of 30-8, 
continued through those of 1836 and 1851, chemists and druggists seem gene¬ 
rally to have overlooked the fact that it was much stronger than the acid called 
one to seven; that the proportions for mixing it were very different, and the 
resulting mixture much stronger than what they had been in the habit of using. 
Simple oxymel prepared by the old and new methods were two different things; 
Acetum Cantharidis could not be prepared with the acid called one to seven, a 
thick unpleasant compound was always the result; and I have strong reason to 
believe that a stronger acid than that ordered in the Pharmacopoeia, and without 
any reference to a definite strength, is commonly used for this preparation, which 
consequently renders it quite empirical. I must myself plead guilty to this 
ignorance until it became my duty to take an active part in going over the 
Materia Medica with a view to the preparation of a new Pharmacopoeia. Much 
pains were taken by the committee formed for this purpose, and a very careful 
list of every article of materia medica found in the three Pharmacopoeias was 
made out, Mr. Squire’s book of the three Pharmacopoeias being the basis of it; 
and the inconsistency and diversity of the preparations of acetic acid were forced 
upon the committee. I then made all the preparations of acetic acid with the 
acids of different strengths, namely, P. L. of 30-8 per cent, and diluted 4*6 per 
cent. : Beaufoy’s, one to seven, of 24*25 per cent, diluted three per cent. ; and 
with the exception of Acetum Cantharidis, which cannot be well made with a 
weaker acid than 30*8, those made with the weaker acid were decidedly prefer¬ 
able, being quite acid enough for all useful purposes, and not inconveniently so 
to the palate. After this I paid a visit to Messrs. Beaufoy and Co., where every 
information I required was most politely and courteously afforded me. I found 
three strengths of acetic acid kept and sold by them to druggists and surgeons, 
namely, 
1st, that labelled 1 acid to 11 water. 
2nd 1 9 
3rd, „ 1 „ 7 „ 
Those marked 1 to 11 and 1 to 7 are usually and almost exclusively sold to 
druggists and surgeons,—the last being generally but erroneously supposed to be 
the Acidum Aceticum of the London Pharmacopoeia, and used as such, but in 
fact corresponding to the Acidum Aceticum of commerce of the Dublin Pharma¬ 
copoeia, and when diluted as directed on the label attached thereto affording 
an acid of only 3*5 per cent.; the first corresponding with Acidum Aceticum 
Forte of the Dublin Pharmacopoeia. The other, marked 1 to 9, is the Acidum 
Aceticum of the London College, and should be marked as the College orders, 15 
parts by weight of acid to 85 water — 3 to 17, or 1 to 5-f, or 23 fl. dr. in 20 fl. oz., 
to afford a diluted acid containing 4*6 per cent of real acid. This last-named 
acid (30*8 per cent) is not generally known in the retail trade ; consequently for 
the last 30 years nearly we have mostly been in error in our pharmaceutical 
practice. I found there were technical trade difficulties in the way of altering 
labels and bringing the subject prominently forward before the pharmaceutical 
public. Mr. Beaufoy had not lost sight of the fact of difference in strength, al¬ 
though the druggists had, and he had labels prepared for the new acid, but never 
used them. At my urgent request however, that they would clearly distinguish 
