188 
BRITISH PHARMACEUTICAL CONFERENCE. 
with other precipitants, and found tartrate of potash to answer very well, though further 
experiments were desirable before accepting the process. 
REPORT ON THE PROCESSES EOR THE PREPARATION 
OF GLACIAL ACETIC ACID. 
BY MR. W. E. HEATHFIELD. 
It is well known that the principal source of acetic acid is wood, which, 
when subjected to destructive distillation in closed iron vessels, yields, by 
the re-arrangement and combination of its elements, a plentiful supply, 
amongst many other products; by this operation a large proportion of 
acetic acid, whether for use in the arts, for culinary purposes, or in the prac¬ 
tice of medicine, is now manufactured. The early process of carbonizing 
split blocks in iron retorts has scarcely been deviated from, and although a 
more recent mode of producing it during the conversion of sawdust into char¬ 
coal has been attempted, it has scarcely been found, generally, sufficiently 
remunerative to justify its continued prosecution. 
The crude acetic acid, obtained by the before-mentioned operation, when 
saturated with lime produces an acetate of lime, which, when decomposed by 
means of sulphate of soda, furnishes acetate of soda, the salt commonly made 
use of for the manufacture of acetic acid, whether officinal or glacial. 
The officinal acetic acid of the British Pharmacopoeia is required to be of 
the specific gravity of L044, and is said to contain 28 per cent, of anhydrous 
acid, equal to about 33 per cent, of the monohydrated or glacial acid, one 
drachm requiring 3L5 measures of the volumetric solution of soda for satu¬ 
ration. 
The officinal acid of the United States Pharmacopoeia is required to be of 
the specific gravity of 1*041, and is said to contain in each 100 parts 36 parts 
of monohydrated acid, equal to about 30^ per cent, of anhydrous acid, but 
this is declared to be a less satisfactory assurance of its strength than its sa¬ 
turating power, which is such that 100 grains ought to saturate 60 grains of 
crystals of bicarbonate of potash, indicating about 30| per cent, of anhydrous 
acetic acid. 
The monohydrated or glacial acetic acid, being a hydrate of acetic acid, 
or C 4 H 3 0 3 HO, has been produced under the auspices of various promoters; 
that principally followed in this country for some years having been as fol¬ 
lows :— 
One ton of purified acetate of soda was fused in an iron pot until it assumed 
a perfectly tranquil appearance; on being poured off, the cooled mass weighed 
11| cwt. One cwt. of this mass being broken up was digested w ith 60 lb. of 
sulphuric acid, of specific gravity 1*848, and was then subjected in a still to 
the requisite heat for the entire distillation of the acetic acid. This product 
was redistilled with a portion of peroxide of manganese, in a chloride of cal¬ 
cium or an oil bath, and the product wns finally distilled from charcoal and 
peroxide of lead. At this point the acid was obtained of great purity, and 
being placed in ice, the greater portion of it solidified, and the fluid part being 
poured off, glacial acetic acid remained of about specific gravity 1*067, con¬ 
taining nearly 98 per cent, of monohydrated acid, or 85 per cent, of anlrydrous 
acid; this acid was colourless, volatile, highly caustic, a solvent of camphor, 
resins, essential oils, its vapour burning with a blue colour, and of considerable 
inflammability. 
The process of the British Pharmacopoeia for the production of monohy- 
flrated acetic acid is somewhat similar, saving that the proportion of sul- 
