One of the principal results of the process of fer mentation is the production of alcohol or spirit of wine, effected by the decomposition of the sugar and the separation of the mucilaginous extractive mat ter of the must in the form of lees. The alcohol may be separated from the wine in a pure state, by distillation; of which latter process, we may here remark, the ancients seem to have been entirely ignorant. Different kinds of wine yield very dit ferent quantities of alcohol: the strong wines of the south, particularly those of Spain and Languedoc, yield the most, namely, one-third of proof spirit.
In transferring the wine from the vat to the cask, it undergoes a new process, which renders it again turbid, and generates the phenomena that marked the former action. A portion of the sugar, though the taste of it has nearly disappeared, remains un decomposed; and this being acted upon by the mu cilaginous extractive matter which still exists in solution, a disengagement of carbonic acid gas, and a fresh deposit of sediment, will he the result. These movements become by degrees less percep tible, but still there goes on an insensible fermen tation, as it is called, which, particularly in the case of the stronger wines, will continue for many years; during which they become much ameliorated. A portion of the colouring matter and tartar is precipitated; the liquor loses its harshness, and the aroma and flavour that are peculiar to it become more apparent. These changes may be accelerated by various artificial methods, especially by the agi tation of the lees, which always contain a quantity of fermentative matter, and by the assistance of heat. Hence the reason why certain strong and austere wines are so much improved and mellowed by being exported on the lees to a warm climate, while the lighter and more delicate wines are gene rally injured by being made to undergo a similar process, or even by the motion occasioned by the removal of them to any considerable distance.
The next step, when wine has attained a sufficient degree of maturity, is to free it from the lees by being racked, as it is termed, into a clean cask; and in order to prevent a renewal of fermentation, it is subjected to the operation of sulphuring:. This process is generally performed by means of sulphur matches applied to the cask into which the wine is to be racked. Should the fermentation still con tinue, this application is renewed as often as may be necessary. Sometimes must, strongly impreg nated with sulphurous acid gas, is added to the wine, which answers the same purpose as the other mode. After sulphuring, the greater proportion of wines require to be farther clarified, or fined, before they attain a due brightness. For this purpose various substances are used, which, by their chemi cal or mechanical action, unite with such materials as disturb the purity of the wine, and precipitate them to the bottom. The substances in general use
are isinglass and the white of eggs, but as these, particularly in warm climates, are-of a putrescent nature, gum arabic has been used instead of them. In Spain the white wines are sometimes clarified with fuller's earth. Powdered marble, gypsum. heated flints, beechwood chips, and a variety of other things are used for the same purpose. The quantity, however, of any of these substances used is very small: one ounce of isinglass, for example, is sufficient for a hundred gallons of wine. Brandy is sometimes mixed with wine; and different wines are as frequently mixed with each other: processes which require great attention and nicety.
With regard to the flavour and the colour of wines, we may state that neither of these two quali ties are inherent to a very great degree in any kind of grapes, with a very few exceptions, but that they are artificially communicated to the wines by the manufacturer. These results are obtained in va rious ways, some of which continue a secret. Its flavour, however, is often generated by the applica tion of bitter almonds, oak chips, orris root, worm wood, &c. while colour is the result of the use of logwood, Brazil wood, elder berry, oak chips, iron, Scc. Both processes, to succeed, require to be managed with particular delicacy and skill.
We should have stated before this time that the vine, the source of the beverage of which we have been treating, does not thrive except between the 35th and the 58th degrees of north latitude, and that it is between these points that the best vine yards are found, and the richest wines are produced. In climates more northerly than that referred to, the grape seldom arrives at full maturity, and if wines are attempted to be made from it, they are weak, liable to sour, and destitute of the generous flavour which characterizes those produced in more favour ed regions. South of the 35th degree, the saccha rine matter predominates, and a complete decom position cannot be effected. The vine improves when transplanted from a cold to a warm climate; but a contrary result takes place when carried fro:n a southern to a northern latitude. The quality of the vine depends also much on the soil and the weather. Light and porous soils are the best: rich manure is prejudicial, and in some districts pro hibited by a public decree. In a cold year, the grape never attains to proper maturity, and the wine produced from it is of a corresponding cha racter. While much rain, fog, and high winds are injurious, a moderate degree of humidity is essen tial to the welfare of the vine. In climates where great drought prevails, the earth is formed into a hollow round the plant, to retain the rain which falls in spring. Undulating ground, with a good southern exposure, is the most favourable.