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204
Vinegar Act allowed as much as one-thousandth part by
weight of oil of vitrol, sulphuric acid (H2 S O4), to be added.
The best vinegar makers do not find it necessary to use oil of
vitrol, but the presence of sulphuric acid—not exceeding
one-thousandth part of the weight of the vinegar—could
not be treated in law as an adulteration. The presence of
this amount of sulphuric acid would greatly sharpen the
acidity of the vinegar, but such acidity would not count,
inasmuch as what the purchaser of "vinegar " demands is
"acetous acid" The presence of mineral acids other than
sulphuric would be an adulteration.
As to the four samples of vinegar submitted for analysis in
1890, none contained more than such traces of sulphuric acid
as would be found combined with lime in ordinary London
drinking water. None contained lead or other poisonous
impurity. The only question therefore that arose was,
What percentage of acetous acid is a purchaser entitled to
when he demands "vinegar ?"
Now "proof vinegar," "standard vinegar," or 6 per
cent. vinegar is known as "No. 24." But other strengths,
mostly by the addition of water, are manufactured and
sold in the trade as No. 22, No. 20, No. 18, and No. 16.
These numbers having respectively 11/12ths, 10/12ths, 9/12ths. and
8/12ths of the acetous acid contained in "proof vinegar" or
"No. 24." And among inferior manufacturers the vinegars
sold under these numbers will fall below the above strengths.
Taking the lowest recognised number, "No. 16," that
number should contain 4 per cent. of real acetous acid
(C2 H4 O2). Thereupon I advised the Sanitary Committee
that all vinegars not containing 4 per cent. of real acetous
acid should be treated as adulterated with added water; but
"hat at present the vendor of sample No. 51, containing