In the Champagne country, the grapes which are to fill one cure are all pressed within the space of two hours, and the must allowed to remain in the cure for a period varying from six or twelve to eighteen hours, according to the temperature, during which it undergoes a process of spontaneous purification, becoming as clear as water. The moment when this is complete is watched for with the utmost care ; it is then drawn off into small casks, which are well sulphured (a process which is hereafter explained), and put into cellars below ground, the bunghole being left open, but covered with a flint stone. The overflowing froth, or yeast, is removed from time to time till December or January, when the chief purchases are made, as then the wine can be tasted and proved. It is then also submitted to the process of fining.
At Tokay the must is allowed to remain in the vat from twenty. four to thirty-six hours, till the first signs of fermentation are mani fested ; it is then drawn off into small ca.sks (which are never sulphured) and placed in a still part of the cellar. The effervescence lasts two or three months.
The fermentation spoken of hitherto is called the primary or active fermentation ; but there is a subsequent one, called the secondary or insensible, which, though obviously a continuation of the former, is less attended to, but yet of great importance as relates to the ripening, keeping, and acidity of the wine. A knowledge of the causes of fer mentation, and the conditions under which it can take place, is essential to the comprehension of the measures necessary for ripening the wine and preserving it in perfection. The subject has been fully explained in Liebig's Chemistry of Agriculture,' and .Mulder's Chemistry of Wine, London, 1859.
When a dry wine is wished, it is necessary that all the sugar should be transformed into alcohol. To do this the fermentation is excited from time to time, by rolling the wine, or returning it to the lees to feed. As the wine contains variable quantities of undecomposed gluten in solution or thrown down to the bottom of the cask, it is only neces sary to stir up the lees to re-excite the fermentation. But lest the point should be passed at which the vinous fermentation is nearly com plete, and the acetous would begin, all the undecomposed ferment is removed. Much of it remains in the vat in which the first and violent fermentation takes place ; when the fermenting liquid is put in casks, these are generally kept nearly full, by frequent additions of fresh juice, so that much of the ferment works out at the bunghole, which is seldom perfectly closed for two or three months. Racking is practised, for valuable wines, as often as three times the first year. 'Phis consists in transferring the wine to a fresh cask. It is in doing this that the practice of sulphuring is mostly adopted. It consists in burning sulphur-matehes or linen steeped in sulphur in the cask previously well rinsed, by which all the oxygen of the atmospheric air is consumed, and a quantity of sulphurous acid gas produced. This must be carefully done, as, if in excess, the wine acquires the taste of sulphur, which it keep for some time. White wines require
most sulphur, especially when very dry. It is proper to transfer the wine immediately to the exhausted cask, otherwise it would speedily get filled again with common atmospheric air. Dr. M'Culloch recom mends the following method, as he remarks that by the common method of tapping it is scarcely possible to draw the wine without mixing a portion of the lees with it :—" To effect it, a cock is introduced into the full cask at the usual place of three or four inches above its bottom, from which a leather hose (a flexible caoutchouc tube would be better) pipe passes into the bung-hole of the empty one. A common pair of bellows may then be so fitted to the bung-hole of the full cask as to force by its action the whole of the clear liquor through the hose into the empty vessel. By this means the least possible disturbance is created, and the wine is at the same time preserved from the injurious contact of atmospheric air." The whole of the wine should not be drawn off, as the cop frequently contains principles which would readily re-excite fermentation. What is left may be employed to form either brandy or vinegar, according to its kind or value. Another means may be used, instead of sulphuring, to preventing the acetone fermentation, namely, the use of sulphite . of potash. A drachm is in general sufficient for a pipe of wine, and it communicates no taste. The utility of both agents consists in absorbing any trace of oxygen. and preventing It acting on the organic substance. Many volatile oils have the power of checking the vinous fermentation, but their odour Is a practical obstacle to their employ ment. They probably act by hindering the development of the fungus (8a.rAareanyeea rini). Alkalies, comblaing with the free acids, the presence of which is so oreential to the process of fermentation. also hinder it, but as they are destructive of the qualities of the wine, they are inadmissible. Black oxide of manganese. though recommended by Dr. M Culled]. should never be used for wine where sulphuring lies been employed, as it would most readily give off oxygen. Hacking can only free the wine from matters which are Insoluble, and either deposited among the lees or floating on the surface. In order to get rid of some other matters held In solution, a different practice is adopted. This constitutes the process of fining. Isinglass In solution in wine, or white of etert, is commonly employed for this purpose. The common and new trines require more isinglass than the tine and old ones. If the wines have been deprived of the tannin extracted from the seeds of the grape, isinglass has no influence in purifying them. If kept in oak casks, however, as is always the rule in France, they extract tannin from their sidter. Numerous powders and com pounds, as well as other exptelients for keeping or improving wines. are detailed in Junin, ' Manual du Sommelier.' The process of fining is always repeated previous to bottling the wine.