is an indication that the
acetic fermentation has not been completed.

The national standard for pure apple cider vinegar calls for not less
than 4 grams acetic acid, 1.6 grams of apple solids, and 0.25 grams of
apple ash per 100 cubic centimeters, along with other characteristics,
as acidity, sugar, and phosphoric acid content. Many states have special
laws regarding the sale of vinegar.

203. Adulteration of Vinegar.--Vinegar is frequently adulterated by
the addition of water, or by coloring spirit vinegar, thus causing it to
resemble cider vinegar. Formerly vinegar was occasionally adulterated by
the use of mineral acids, as hydrochloric or sulphuric, but since acetic
acid can be produced so cheaply, this form of adulteration has almost
entirely disappeared. Colored spirit vinegar contains merely a trace of
solid matter and can be readily distinguished from cider vinegar by
evaporating a small weighed quantity to dryness and determining the
weight of the solids. Occasionally, however, glucose and other materials
are added so as to give some solids to the spirit vinegar, but such a
vinegar contains only a trace of ash[18]. Attempts have also been made
to carry the adulteration still further by adding lime and soda to give
the colored spirit vinegar the necessary amount of ash. Malt, white
wine, glucose, and molasses vinegars when properly manufactured and
unadulterated are not objectionable, but too frequently they are made to
resemble and sell as cider vinegar. This is a fraud which affects the
pocketbook rather than the health. For home use apple cider vinegar is
highly desirable. There is no food material or food adjunct, unless
possibly ground coffee and spices, so extensively adulterated as
vinegar.

Vinegar has no food value whatever, and is valuable only for giving
flavor and palatability to other foods, and to some extent for the
preservation of foods. It is useful in the household in other ways, as
it furnishes a dilute acid solution of aid in some cooking and baking
operations for liberating gas from soda, and also when a dilute acid
solution is required for various cleaning purposes.

Vinegar should never be kept in tin pails, or any metallic vessel,
because the acetic acid readily dissolves copper, tin, iron, and the
ordinary metals, producing poisonous solutions. Earthenware jugs,
porcelain dishes, glassware, or wooden casks are all serviceable for
storing vinegar.

204. Characteristics of Spices.[7