190 
BRITISH PHARMACEUTICAL CONFERENCE. 
An acid containing 
GO 
per cent, monohvdrated acid i 
S of S] 
3. gr. 1*0G7. 
99 
55 
55 
55 
59 
55 
5% 
1.064. 
59 
55 
50 
5 5 
55 
55 
95 
1*060. 
55 
55 
45 
55 
55 
59 
59 
1*055. 
55 
55 
4-0 
y> 
55 
55 
99 
1*051. 
59 
55 
35 
55 
55 
55 
59 
1*046. 
55 
30 
55 
59 
55 
55 
1*040. 
59 
59 
25 
55 
59 
55 
59 
1*034. 
59 
55 
20 
59 
55 
55 
55 
1*027. 
59 
55 
10 
95 
59 
95 
55 
1-01G. 
59 
59 
5 
55 
55 
55 
59 
1*007. 
Thus an acid of about 80 per cent, lias the highest specific gravity, but 
between 90 and 75 per cent, there is but little variation. 
Molleret found that 100 parts of glacial acid of sp. gr. 1*062 formed, with 
32*25 parts water, a mixture of the density of 1079, and with 112*2 parts 
water a mixture whose density is the same as that of the acid itself, viz. 1063. 
Thus we are called upon for a more definite means of determining the 
strength of this acid than that of specific gravity, and in ordinary examina¬ 
tions the volumetric method with caustic soda is adequate for the purpose. 
It is certainly open to the objection, that neutral acetates bear an alkaline 
reaction on litmus, but with care this mode of testing is little liable to any serious 
source of error. Dr. Ure made use of ammonia, and thought most highly of 
the accuracy of his process. Dr. Mohr suggests the use of carbonate of 
baryta or lime, and the determination by this means is considered most reli¬ 
able. Mr. C. G. Williams recommends a standard solution of lime syrup, 
which seems to be a ready means of estimation. In a report by Mr. John 
Baker, in the Pharm. Trans, for October, 1844, he exhibits great accuracy in 
estimations of this acid by means of carbonate of soda, and I can confirm the 
results of his experiments with this salt. Tn the United States Pharmaco¬ 
poeia bicarbonate of potass is recommended, and although any salt containiug 
carbonic acid is somewhat open to objection for estimating acetic acid, this 
latter salt is perhaps the least so. 
Next to the method proposed b}^ Melsens, that of the Pharmacopoeia is 
the most easy of adoption. Ho process hitherto suggested will secure a pro¬ 
duct of uniformity without some details requiring attention being followed, 
and no operation hitherto suggested has produced an acid of determinate 
strength without subsequent separation of the stronger from the weaker por¬ 
tions. In the present state of our experience we may be satisfied to follow 
the rule laid down for its production, taking care that the estimation of its 
strength, by whatever means attempted, be free from the sources of error 
pointed out. We can well afford to dismiss the taking of its specific gravity, 
and although the solidification of it at certain temperatures assists us in 
forming an opinion of its strength, it is too conspicuous a standard of com¬ 
parison on which to lay much stress. To its saturating power, in one form or 
another, we are at present compelled to resort. 
The President, after referring to the fulness of detail which characterized Mr. Heath- 
field’s monograph, stated that the estimation of the strength of acetic acid had received 
his attention, and he had found that the best results were obtained by saturating the acid 
with carbonate of baryta. 
Mr. T. B. Groves thought that the process of the Dublin Pharmacopoeia, in which 
anhydrous acetate of lead and hydrochloric acid were used, answered well. 
Mr. IIeatiifield replied that the chance of getting traces of chlorine was an objec¬ 
tion to this plan. At present, nearly all the acid sold here was imported from the 
Continent, and there was every reason to believe that it was made by Melsens’ process. 
Its properties with regard to solidification were singular, and apparently capricious. An 
