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45
bined acid (that combined with the potash and other bases
belonging to the vinegar) had been added to the vinegar
as free sulphuric acid. This latter portion of estimated
free sulphuric acid added to the sulphuric acid found
actually free in the vinegar constitute the percentage of
"added sulphuric acid."
The British Pharmacopoeia of 1885, with regard to
sulphuric acid in vinegar, stipulates that 48 measures of the
vinegar shall not precipitate more barium than that in
one measure of the solution of chloride of barium. This
gives .0816 per cent. as the maximum allowable of total
sulphuric acid, reckoned as H2 SO4, and allows liberally
for a very hard water. It will be seen that the Pharmacopœial
maximum is less than the .1 per cent. allowed by
the old Vinegar Act.
Some vinegars are made up with acetic acid obtained
by the destructive distillation of wood. Acetic acid of
this origin is known as "pyroligneous acid," and in its
crude form it is contaminated with tarry products. By the
resources of modern chemistry such acetic acid is perfectly
purified from all contamination, and it is then quite indistinguishable
medically, dietetically, or chemically from
acetic acid as obtained by fermentation and as contained
in pure malt vinegar. Such vinegars are made up to contain
6 per cent. of acetic acid. They do not contain any
of the vegetable extracts which malt vinegars contain, and
they contain no sulphuric acid nor any sulphates, except
such minute traces as were contained in the water with
which the strong acetic acid was diluted, or as may have
been ignorantly imported in the caramel with which they
were coloured. Such vinegars, unless sold as "malt
vinegar," cannot be prosecuted. They are harmless and
perfectly wholesome; in fact, they are much more wholesome
than the "genuine malt vinegars" which are brewed
with gypsum. And they are cheap. They are coloured
and flavoured according to the fancy of the manufacturer.
The trading community of St. James's is much indebted
to the learned magistrate at Great Marlborough Street for