It is well known that bottles in which wine has been kept, are usually cleaned by means of shot, which by its rolling motion detaches the super-tartrate of potash from the sides of the bottles. This practice, which is generally pursued by wine-merchants, may give rise to serious consequences, as will become evident from the following case:[38]
"A gentleman who had never in his life experienced a day's illness, and who was constantly in the habit of drinking half a bottle of Madeira wine after his dinner, was taken ill, three hours after dinner, with a severe pain in the stomach and violent bowel colic, which gradually yielded within twelve hours to the remedies prescribed by his medical adviser. The day following he drank the remainder of the same bottle of wine which was left the preceding day, and within two hours afterwards he was again seized with the most violent colliquative pains, headach, shiverings, and great pain over the whole body. His apothecary becoming suspicious that the wine he had drank might be the cause of the disease, ordered the bottle from which the wine had been decanted to be brought to him, with a view that he might examine the dregs, if any were left. The bottle happening to slip out of the hand of the servant, disclosed a row of shot wedged forcibly into the angular bent-up circumference of it. On examining the beads of shot, they crumbled into dust, the outer crust (defended by a coat of black lead with which the shot is glazed) being alone left unacted on, whilst the remainder of the metal was dissolved. The wine, therefore, had become contaminated with lead and arsenic, the shot being a compound of these metals, which no doubt had produced the mischief."
TEST FOR DETECTING THE DELETERIOUS ADULTERATIONS OF WINE.
A ready re-agent for detecting the presence of lead, or any other deleterious metal in wine, is known by the name of the wine test. It consists of water saturated with sulphuretted hydrogen gas, acidulated with muriatic acid. By adding one part of it, to two of wine, or any other liquid suspected to contain lead, a dark coloured or black precipitate will fall down, which does not disappear by an addition of muriatic acid; and this precipitate, dried and fused before the blowpipe on a piece of charcoal, yields a globule of metallic lead. This test does not precipitate iron; the muriatic acid retains iron in solution when combined with sulphuretted hydrogen; and any acid in the wine has no effect in precipitating any of the sulphur of the test liquor. Or a still more efficacious method is, to pass a current of sulphuretted hydrogen gas through the wine, in the manner described, p. [70], having previously acidulated the wine with muriatic acid.
The wine test sometimes employed is prepared in the following manner:—Mix equal parts of finely powdered sulphur and of slacked quick-lime, and expose it to a red heat for twenty minutes. To thirty-six grains of this sulphuret of lime, add twenty-six grains of super-tartrate of potassa; put the mixture into an ounce bottle, and fill up the bottle with water that has been previously boiled, and suffered to cool. The liquor, after having been repeatedly shaken, and allowed to become clear, by the subsidence of the undissolved matter, may then be poured into another phial, into which about twenty drops of muriatic acid have been previously put. It is then ready for use. This test, when mingled with wine containing lead or copper, turns the wine of a dark-brown or black colour. But the mere application of sulphuretted hydrogen gas to wine, acidulated by muriatic acid, is a far more preferable mode of detecting lead in wine.
M. Vogel[39] has lately recommended acetate of lead as a test for detecting extraneous colours in red wine. He remarks, that none of the substances that can be employed for colouring wine, such as the berries of the Vaccinium Mirtillus (bilberries), elderberries, and Campeach wood, produce with genuine red wine, a greenish grey precipitate, which is the colour that is procured by this test by means of genuine red wines.
Wine coloured with the juice of the bilberries, or elderberries, or Campeach wood, produces, with acetate of lead, a deep blue precipitate; and Brazil-wood, red saunders, and the red beet, produce a colour which is precipitated red by acetate of lead. Wine coloured by beet root is also rendered colourless by lime water; but the weakest acid brings back the colour. As the colouring matter of red wines resides in the skin of the grape, M. Vogel prepared a quantity of skins, and reduced them to powder. In this state he found that they communicated to alcohol a deep red colour: a paper stained with this colour was rendered red by acids and green by alkalies.
M. Vogel made a quantity of red wine from black grapes, for the purpose of his experiments; and this produced the genuine greyish green precipitate with acetate of lead. He also found the same coloured precipitate in two specimens of red wine, the genuineness of which could not be suspected; the one from Chateau-Marguaux, and the other from the neighbourhood of Coblentz.
SPECIFIC DIFFERENCES, AND COMPONENT PARTS OF WINE.
Every body knows that no product of the arts varies so much as wine; that different countries, and sometimes the different provinces of the same country, produce different wines. These differences, no doubt, must be attributed chiefly to the climate in which the vineyard is situated—to its culture—the quantity of sugar contained in the grape juice—the manufacture of the wine; or the mode of suffering its fermentation to be accomplished. If the grapes be gathered unripe, the wine abounds with acid; but if the fruit be gathered ripe, the wine will be rich. When the proportion of sugar in the grape is sufficient, and the fermentation complete, the wine is perfect and generous. If the quantity of sugar be too large, part of it remains undecomposed, as the fermentation is languid, and the wine is sweet and luscious; if, on the contrary, it contains, even when full ripe, only a small portion of sugar, the wine is thin and weak; and if it be bottled before the fermentation be completed, part of the sugar remains undecomposed, the fermentation will go on slowly in the bottle, and, on drawing the cork, the wine sparkles in the glass; as, for example, Champagne. Such wines are not sufficiently mature. When the must is separated from the husk of the red grape before it is fermented, the wine has little or no colour: these are called white wines. If, on the contrary, the husks are allowed to remain in the must while the fermentation is going on, the alcohol dissolves the colouring matter of the husks, and the wine is coloured: such are called red wines. Hence white wines are often prepared from red grapes, the liquor being drawn off before it has acquired the red colour; for the skin of the grape only gives the colour. Besides in these principal circumstances, wines vary much in flavour.