A number of herrings were cleaned on the 10th of July, 1819; and
without being salted, were immersed for three hours in distilled
pyroligneous acid, specified gravity 1012. When withdrawn they were
softened and not so firm as fish taken out of common pickle. They
were hung up in the shade; July and August were hot months, but the
herrings had no signs of putrefaction about them, but had a very
wholesome smell, combined with that of the acid. One being broiled
the empyreumatic smell was very strong. The rest, after six months,
were in complete preservation.
It was afterwards found that the period of immersion had been
too long. If the fish are simply dipped in acid of specific
gravity 1012, and dried in the shade, it is sufficient for their
preservation; and such herrings, when boiled, are very agreeable and
have not the disagreeable empyreuma of the former.
A number of haddocks were cleaned, split, and slightly sprinkled
with salt for six hours; then being drained, dipped for about three
seconds in pyroligneous acid, and hung in the shade for eight
days. On being broiled, they were of an uncommonly fine flavour,
delicately white, and equal to the highly esteemed Finnan Haddock.
Herrings were cured in the same way as the haddocks. After being
dried in the shade for two months, they were equal in quality and
flavour to the best red herrings. The fish retained the shining and
fresh appearance they had when taken from the sea.
A piece of fresh beef was dipped for one minute in pyroligneous acid
of specific gravity 1012, in July 1819. On March 4, 1820, it was as
free from taint as when first immersed. No salt was used in this
experiment. A piece of beef was dipped in at the same time in pure
vinegar, of specific gravity 1009. It was perfectly free from taint
on the 18th of November. This experiment indicates antiseptic powers
in pure vinegar; some haddocks were cured with it, which remained
free from taint, but when cooked had an insipid taste.
When beef is partially salted, and then steeped for a short time in
the pyroligneous acid, after being drained and cooked, it has the
same flavor as Hamburg beef.
Mr. Ramsay has no doubt, that with proper modifications, the use of
the acid may be extended to the preservation of every species of
animal food.
In order to ascertain whether the volatile oil in the pyroligneous
acid, or the acid itself, was the agent to prevent putrefaction,
Mr. Ramsay dipped haddocks and fresh beef in pure vinegar of
specific gravity 1009. When fish were allowed to remain in the
vinegar a few minutes, he observed that the muscular fibre was
immediately acted on, a partial solution of the fish took place, and
the acid became milky. When vinegar of a stronger quality was used,
the fish was entirely dissolved, particularly if aided by heat. Both
fish and beef which were dipped in vinegar, of specific gravity
1009, and which were afterwards dried in a summer heat, remained for
a long time after perfectly free from taint.
Mr. Stodart has repeated some of these experiments, and especially
those relating to the haddocks, with perfect success in London.