This section is from the book "Meals Medicinal", by W. T. Fernie. Also available from Amazon: Meals Medicinal: With "Herbal Simples" Curative Foods From the Cook in Place of Drugs From the Chemist.
Vinegar (Vin-Aigre), Sour Wine, is commonly procured from an infusion of Malt which has previously undergone the vinous fermentation, or perhaps from apple cider. White vinegar is the best sort, then Malt vinegar, and least acceptable, though chemically pure, is the diluted acetic acid got from the products of the dry distillation of wood. More properly, Vinegar ought to be obtained by the acetic fermentation of wine, but this is difficult to procure. "Ordinary English' vinegar," says Dr. A. Blyth, speaking authoritatively, "as far as the kitchen is concerned, is a chemical monstrosity." We should try to buy French vinegar from a respectable Italian warehouseman. Herbal vinegar must not be boiled. The acid of vinegar, being a fermentation 'acid, renders the digestion of many foods with which it is taken more difficult, whilst vegetable acids, such as lemon juice, and citric acid, or tartaric acid, do not cause that objectionable effect. Thus a cucumber salad (to be made with the vegetable freshly cut) when dressed with vinegar is so difficult of digestion as to be for some persons almost poisonous; whilst if dressed with lemon juice, it can be easily and comfortably digested by the very same persons.
Vinegar is the antiseptic ingredient in pickles; when applied externally its cooling effects, and fragrant aroma are refreshing; they even serve to revive a person faint from heat, or other aggressive surroundings. Thus it is told in Pickwick, that at Manor Farm, Dingley Dell, "the landlady proceeded to vinegar the forehead, beat the hands, titillate the nose, and unlace the stays of the maiden aunt".
The hindering effect of Vinegar on our salivary digestion of starches is very powerful, and the bearing of this fact on our using it in salads together with the vegetable carbohydrates is evident. Nevertheless, salads are commonly seasoned with vinegar in plenty, and they are generally eaten together with a free use of bread. The acid may perhaps aid the digestion of the vegetable albumin in the salad, but it is obvious that at the same time this vinegar would altogether prevent any salivary action on the bread taken with the salad. The difficulty may not be a matter of much moment to a person with strong digestive powers, who has abundant digestive resources: but others who are of weak digestive capabilities, must be sparing in their use of such vinegar in salads, and other sour dishes, when bread or potatoes accompany the same, or when a starchy pudding follows. One compensating result of Vinegar on the fibre of meat, and the tough cellulose of vegetables, is its softening action thereupon. From the Arcana Fairfaxiana, of three centuries back, as already quoted, we learn "how to quench thirst when drink is improper." "Pour vinegar into the palm of the hand, and sniff it up into the nostrils, and wash the mouth with the same (though not swallowing any); 'tis inconceivable how much it will allay thirst." By a strange misprint, in an edition of the Bible, published at the Clarendon Press, Oxford, in 1717, the heading of the "Parable of the Vineyard," in St. Luke's gospel, chapter xx, is made to read, Parable of the Vinegar".
Because of its being a product of acid fermentation outside the body, Vinegar will sometimes serve to correct the sour fermentation which occurs from imperfect digestion of swallowed foods, such as sugars, starches, and melted fats, by giving a teaspoonful of the pure Malt product, by itself, or with an equal quantity of cold water. This proceeding may be said to be adopted on the principle of "setting a thief to catch a thief." Acetic acid, as sometimes substituted for the vinegar of fermentation, is obtained by the oxidization of alcohol, and the distillation of organic matters in hermetically-sealed vessels. This acid is inflammable, so that great caution is needed when adding it to boiling sugar; it is to be used only in small quantities.
"Before proceeding to the Legacy Duty Office about proving the will of his late wife, Mr. Weller, senior, and his fellow coachmen, as witnesses, bethought themselves of having a drop of beer, and a little bit of cold beef, or a oyster, These viands were promptly produced, and the luncheon was done ample justice to. If one individual evinced greater powers than another it was the coachman with the hoarse voice, who took an imperial pint of vinegar with his oysters, and did not betray the least emotion" (Pickwick). Although the acetic acid which vinegar contains is ultimately oxidized in the body, with a production of alkaline compounds, yet still there is reason to believe, that through its being an acid of fermentation it has an unfavourable influence in gout, and may even induce an attack, not otherwise imminent.