09] The English Housekeeper, p. 352, 354.

_Adulteration of Vinegar._

Vinegar, as prepared in this country, from malt, should be of a pale
brown colour, perfectly transparent, of a pleasant, somewhat pungent,
acid taste, and fragrant odour, but without any acrimony. From the
mucilaginous impurities which malt vinegar always contains, it is apt,
on exposure to air, to become turbid and ropy, and at last vapid. The
inconvenience is best obviated by keeping the vinegar in bottles
completely filled and well corked; and it is of advantage to boil it in
the bottles a few minutes before they are corked.

Vinegar is sometimes largely adulterated with sulphuric acid, to give it
more acidity. The presence of this acid is detected, if, on the addition
of a solution of acetate of barytes, a white precipitate is formed,
which is insoluble in nitric acid, after having been made red-hot in the
fire. (See p. 159.) With the same intention, of making the vinegar
appear stronger, different acrid vegetable substances are infused in it.
This fraud is difficult of detection; but when tasted with attention,
the pungency of such vinegar will be found to depend rather on acrimony
than acidity.

Distilled vinegar, which is employed for various purposes of domestic
economy, is frequently distilled, not in glass, as it ought to be, but
in common stills with a pewter pipe, whence it cannot fail to acquire a
metallic impregnation.

One ounce, by measure, should dissolve at least thirteen grains of white
marble.

It should not form a precipitate on the addition of a solution of
acetate of barytes, or of water saturated with sulphuretted hydrogen.
The former circumstance shews, that it is adulterated with sulphuric
acid; and the latter indicates a metal.

The metallic impregnation is best rendered obvious by sulphuretted
hydrogen, in the manner stated, page 69. The distilled vinegar of
commerce usually contains tin, and not lead, as has been asserted.

_Adulteration of Cream._

Cream is often adulterated with rice powder or arrow root. The former is
frequently employed for that purpose by pastry cooks, in fabricating
creams and custards, for tarts, and other kinds of pastry. The latter is
often used in the London dairies. Arrow-root is preferable to rice
powder; for, when converted with milk into a thick mucilage by a gentle
ebullition, it imparts to cream, previously diluted with milk, a
consistence and apparent richness,