Note 91 — Chapter V · The Alcoholic Ferments.

In experiments of this kind there is always a slight increase in the volume of air in the jar. This increase may be very perceptible even when the experiment made with fresh grapes, in August, for instance, causes no fermentation due to the action of yeast. After the oxygen of the air has been absorbed and replaced by carbonic acid gas, either by direct oxidation or by the action of moulds, the grapes, although crushed, act like fruits plunged into carbonic acid gas[92], and this effect is even more marked in the case of imperfectly crushed grapes. The reason is, that the crushing is never so perfect as to injure all the cells of the parenchyma. We may easily convince ourselves that the experiment on the liberation of carbonic acid gas and the formation of alcohol by grapes and fruits in general when plunged into carbonic acid succeeds very well in the case of fragments of fruits or grapes, and succeeds better the less the parts are crushed.