On the contrary, in those which have acquired the largest amount of alcohol possible by fermentation (between 15 and 16 per cent.), no new spirit is formed at the expense of the sugar, except in case of loss of strength by evaporation or other enfeebling cause.
Summary of Rules for the treatment of mellow white wines, according to Boireau:
1. They should be stored in perfectly closed places, in strong, well hooped casks.
2. The casks should always be kept tightly bunged, and constantly full, by frequent and regular ullings, with bright wine of the same quality, and having the same temperature.
3. They should become bright, be protected against secondary fermentations, and freed from the yeast which they contain by rackings during the first year, according as their lees are deposited. Fining should not be resorted to except when they cannot be cleared by racking at the proper time (rigorously protected from contact with the air) into a cask sulphured with a double square of a sulphur match.
4. When they have been three or four years in wood, if they are not then bottled, they should be racked and transferred to tuns where they receive the same care; the tuns should be first tempered with wines of the same class.
5. They must be constantly watched and frequently tasted to assure one’s self that they do not enter into fermentation; if they do, they must be racked at once.
Racking.—When they remain calm after the insensible fermentation is terminated, whether they are old or young, they should be racked three times each year; first, at the sprouting of the vine in the spring, in March, before the equinox; secondly, at the flowering of the vine in June, before the summer solstice; and thirdly, at the ripening of the grape in September, before the autumnal equinox. (See [Racking].)
CHAPTER VIII.
CASKS.
Casks are almost universally made of oak, though other material has been tried, but generally to be abandoned in favor of the first named. Large, covered tanks of redwood are used to some extent in California for storing red wine, being first well steamed to extract the coloring matter of the wood, but they are not considered desirable, and had better be replaced by oak casks.