Page:A Treatise on the Culture of the Vine and, and the Art of Making Wine.pdf/211

 the empty part of the vat, till it flows over the sides, and falls, by its weight, to the lowest part of the cellar.

It is to the formation of this gas, which carries off a portion of oxygen and carbon from the constituent parts of the must, that should be referred the principal changes occurring in fermentation; retained in the liquor, by every means which can be opposed to its evaporation, it contributes to preserve in it the aroma, and a portion of alcohol, which would exhale with it.

It is to this gas which brisk wines owe their property of frothing; being sealed up in glass before the fermentation is completed, the gas develops itself slowly, and remains compressed in the liquid, till the moment when relieved from compression by the removal of the cork, it escapes with force.

This acid gas gives to all liquors, impregnated with it, a tartish taste. Mineral waters owe to it their principal virtue; but it would give a very vague idea of its state in the wine, to compare its effects to those produced by its liberal dissolution in water. The carbonic acid, which disengages itself from wine, holds, in solution, a considerable portion of alcohol.

Chaptal believes himself to have been the first to demonstrate this fact, by shewing, that