The temperature of the must soon begins to rise, and the fermentative agencies break up its glucose into alcohol and carbonic acid gas.  There is a bubbling and seething in the liquid during this action, which gradually subsides.  The increase of temperature in the fermented fluid begins to abate; the skins and husks subside to the bottom of the vat; the liquid itself becomes slightly less turbid—­and the first stage of wine-making is at an end.

A clearer insight into this important part of the process will perhaps be gained by noting some of the practices followed on the Continent, as regards the duration of the vattage.  The length of time the various contents—­whether they be the grape juice alone, or the grape juice together with the skins and stalks—­remain within the fermenting-vat, varies greatly in different parts.  In the Champagne country, the must is allowed to stand for twelve or eighteen hours, during which time a froth arises to the top and a sediment descends to the bottom.  Without disturbing either of these, the precious liquid is carefully withdrawn into small barrels, and the fermentation is then allowed to proceed.  This purification is one of the most important matters connected with the making of champagne.

The Medoc districts, in the Bordeaux territory, produce the finest of the clarets.  The grapes are detached from the stalks, and subjected to pressure.  The must is put into the fermenting-vat, to which is added the murk resulting from the pressing, and the stalks which were previously separated from the berries.  The time necessary for vinification varies; in good years it is no longer than four or five days, and the future wine will then be at its best with regard to taste, delicacy, and softness.

In one case, that of the Red Hermitage wine of France, the grapes are unstalked and crushed before being placed in the vat.  The contents of the latter are then stirred twice a day, and ultimately once a day.  This is continued for about a month, and in one of the best vineyards for forty days.  This long “cuvage” appears necessary from the fact that the large amount of sugar in the must is but slowly transformed into alcohol.

There is a curious incident which occurs in connection with the world-renowned wines of Burgundy, which is worth recording.  As the fermentation proceeds, the murk, as in all similar fermentations, rises to the surface of the vat, and forms what is called the “hat,” or chapeau.  The fermentation proceeds till all is ready for the wine to be drawn.  At this time the “hat” is so dense that it will bear the weight of two or three men.  Each of them now begins working with one foot till he gets it through the crust, and the whole chapeau is eventually broken up and mixed with the wine.