One of the many interesting features of Champagne is that although a white wine it is made largely from black grapes. The grapes are pressed as soon as they are picked, in such a way as to separate the juice from the skins, which latter contain the colouring matter, and the juice is immediately run off into large fermenting vats, and thence into casks.
Fermentation begins at once, and transforms the sugar of the grape juice into alcohol and carbonic acid gas. The result is the alcohol remains in the wine, while the carbonic acid gas loses itself in the air. To retain part of this carbonic acid gas in the wine is the chief feature of the art of making ” Sparkling Wine.” This is effected by bottling the wine at an early date, namely in the springtime following the vintage. Fermentation continues within the bottle, and as the carbonic acid gas is unable to escape, it remains in solution with the wine and renders it ” Sparkling.”
There is thus caused a certain amount of sediment in the wine, which is removed by stacking the bottles neck downwards, which are shaken daily for some two months or so, when the time comes to operate the wine for export, until the whole of the deposit settles on the cork. The deposit is subsequently ejected from the bottle, and the necessary sweetening matter, namely a small quantity of candy sugar dissolved in Champagne of the best quality, is added. This process is called ” disgorging.” One method of doing so is by a process of freezing the deposit to the cork and removing the cork and sediment in one frozen unit.
A new cork is then placed in the bottle, and the Champagne is ready for consumption.
From the Book “Harry” of Ciro’s ABC of Mixing Cocktails by Harry MacElhone, London, 1921.