A popular writer remarks, " When my stomach is not in good temper, it generally desires to have red wine; but when in best health, nothing affronts it more than to put Port into it; and one of the first symptoms of its coming into adjustment, is a wish for white wine." On the contrary, a gentleman lately informed me, that when his stomach was not "right," the smallest quantity of Port wine produced acidity, while, at all other times, it was much more grateful to him than any species of white wine. Every physician must be practically aware of the caprice which the stomach displays in its morbid conditions; but as a general rule, it may be stated, that white deserve a preference over red wines, because the latter, being pressed, and subjected to a stronger fermentation to extract the colouring principle from the husk, are necessarily more loaded with extractive and astringent matter; and as this remains in the stomach after the liquid portion of the wine is absorbed (97), it will be liable to occasion disturbance.

1 For an account of which, the reader is referred to a most ingenious and interesting essay by Dr. Maculloch, entitled "Remarks on the Art of making Wine; with Suggestions for the Application of its Principles to the Improvement of Domestic Wines".

259. The odour, or bouquet, and flavour, which distinguish one wine from another, evidently depend upon some volatile and fugacious principle not hitherto investigated by the chemist: this, in sweet and half-fermented wines, is immediately derived from the fruit, as in those from the Frontignan and Muscat grapes; but in the more perfect wines, as in Claret, Hermitage, Rivesaltes, and Burgundy, it bears no resemblance to the natural flavour of the fruit, but is altogether the product of the vinous process. The menstruum of this volatile principle is, doubtless, in most instances, the alcohol contained in wines; but its quantity is so minute as to be incapable of separation. In this latter case it frequently appears to produce a very remarkable effect upon the nervous system, and may, possibly, be hereafter discovered to be a new principle, of extraordinary powers: such an opinion, at least, is sanctioned by the well-known effects of Burgundy; the excitement produced by this wine being peculiar, and not bearing any relation to the proportion of alcohol contained in it. Some wines are artificially flavoured by the introduction of foreign ingredients, as by almonds in Madeira wines, as well as in those of Xeres and Saint Lucar; and hence their well-known nutty flavour.

Among the ancients, and in modern Greece, it is at this day the fashion to give a resinous flavour, by the introduction of turpentine into the casks. These wines were supposed to assist digestion, to restrain morbid discharges, to provoke urine, and to strengthen the bowels; but Dioscorides informs us, that they were known to produce vertigo, pain in the head, and many evils not incidental to the potations of the same vinous liquor, when free from such admixtures.

260. The quantity of acid contained in wines has been supposed capable of diminishing their salubrity, and in some cases of rendering them eminently noxious. There can be no doubt, that where there exists a considerable excess of gallic or malic acids, or where acetic acid has been generated during a protracted fermentation, such wine will be obnoxious to the stomach; but where the acid arises from the nature of the fruit, it surely cannot merit the odium which popular opinion would assign to it. What, for instance, is the acid contained in Madeira, and against which so many mighty objections have been urged? an atom merely of tartar! And yet the person who fancies that his digestion can be deranged by its action, will swallow twenty times the quantity of the same ingredient in some other shape, with perfect indifference and impunity. Sir Anthony Carlisle 1, who has carried his prejudices against acids farther than any other writer, says, "Long-continued and watchful observation induces me to conclude, that the acid qualities of fermented liquors are no less injurious than the spirit which they contain." If the process of reasoning, by which he arrived at such a conclusion, be not more correct than the experiments which enabled him to ascertain the quantities of acid matter in different fermented liquors, it cannot merit the confidence of the public.

His table, which was constructed to exhibit "gross proof (of error?) of the relative quantities of free acid in ordinary fermented drinks," is a chemical curiosity. The tyro who has attended a single course of lectures will at once perceive, by casting his eyes over this table, that its results are wholly inconsistent with the doctrine of chemical equivalents. He tells us, that " a moderate-sized glassful, containing two ounces (avoirdupois) of Port wine, required, for neutralization, three grains of Henry's calcined magnesia, or six grains of carbonate of potass, or four grains of subcarbonate of soda, or nine grains of prepared chalk." Now these are not the relative proportions in which such bases could, by any possibility, unite with any acid; but granting, for the sake of argument, that our scales of equivalents are in error, and that the true proportions have been ascertained by the experiments in question, we shall then discover, that the tabulated results are not consistent with themselves; for in a second experiment, made with vidonia, the numbers indicating the combining weights of these substances are not, as in the former case, in the relation of 3, 6, and 4, but in that of 5, 7, and 6; in the third experiment with Sherry, in that of 3, 5, and 4; in a fourth with London porter, in that of 3, 3.5, and 3; and in the last, with brewers' fresh table-beer, the proportions are 2.5, 2, and 2. Sir Anthony was aware of these discordances; and he attempts to explain them by supposing that they may be "owing to the varying affinities of native acids, derived from the fruits, and the acid products of fermentation, as they regarded the several tests." It is almost unnecessary to state, that this supposition is in direct variance with the acknowledged doctrine of definite proportionals, and the fundamental principle of chemical combinations.