pure water exposed in vessels immediately above the fermenting must, was, after two or three days, impregnated with carbonic acid; and that it was sufficient to place the water, so impregnated, aside, in uncorked bottles, to procure a very good vinegar. At the same time that the vinegar is formed, flakes, of a nature very analogous to fibre, are abundantly precipitated.
The experiment sufficiently proves, that the carbonic acid carries off alcohol with it, and a small portion of leaven; and that these two principles, necessary to the formation of active acid, produce it when decomposed by the contact of the air. But another question arises, and one which can only be determined by experiment. Is the alcohol held in solution by the gas, or does it owe its volatilization only to the heat? It had been observed by Dom. Gentil, in 1779, that if a glass bell was turned down, above the must in fermentation, the interior walls were filled with a liquid, which had the odour and properties of the first phlegm which passes over in the distillation of wine; and M. Humboldt has proved, that if the froth of Champagne is received in bells, and these surrounded with ice, alcohol is precipitated by the simple impression of the cold.
It appears, then, that the alcohol is dissolved in the carbonic acid, and that it is to it that the vinous
