THEORY OF FERMENTATION 319 



Encouraged by this result, we undertoook fresh experi- 

 ments on grapes, on a melon, on oranges, on plums^and 

 on rhubarb leaves, gathered in the garden of the Ecole 

 Normale, and, in every case, our substance, when immersed 

 in carbonic acid gas, gave rise to the production of alcohol 

 and carbonic acid. We obtained the following surprising 

 results from some prunes de Monsieur: 1 On July 21, 1872, 

 we placed twenty-four of these plums under a glass bell, 

 which we immediately filled with carbonic acid gas. The 

 plums had been gathered on the previous day. By the side 

 of the bell we placed other twenty-four plums, which were 

 left there uncovered. Eight days afterwards, in the course 

 of which time there had been a considerable evolution of 

 carbonic acid from the bell, we withdrew the plums and 

 compared them with those which had been left exposed 

 to the air. The difference was striking, almost incredible. 

 Whilst the plums which had been surrounded with air (the 

 experiments of Berard have long since taught us that, under 

 this latter condition, fruits absorb oxygen from the air 

 and emit carbonic acid gas in almost equal volume) had 

 become very soft and watery and sweet, the plums taken 

 from under the jar had remained very firm and hard, 

 the flesh was by no means watery, but they had lost much 

 sugar. Lastly, when submitted to distillation, after crush- 

 ing, they yielded 6.5 grammes (99.7 grains) of alcohol, 



tbat have been immersed in an atmosphere of carbonic acid gas have exactly 

 the flavour and smell of the vintage; the reason is that, in the vintage tub, 

 the grapes are immediately surrounded by an atmosphere of carbonic acid 

 gas, and undergo, in consequence, the fermentation peculiar to grapes that 

 have been plunged in this gas. These facts deserve to be studied from a 

 practical point of view. It would be interesting, for example, to learn 

 what difference there would be in the quality of two wines, the grapes of 

 which, in the one case, had been perfectly crushed, so as to cause as great 

 separation of the cells of the parenchyma as possible; in the other case, 

 left, for the most part, whole, as in the case in the ordinary vintage. The 

 first wine would be deprived of those fixed and fragrant principles produced 

 by the fermentation of which we have just spoken, when the grapes are 

 immersed in carbonic acid gas. By such a comparison as that which we 

 suggest we should be able to form d priori judgment on the merits of the 

 new system, which has not been carefully studied, although already widely 

 adopted, of milled, cylindrical crushers, for pressing the vintage. 



We hare sometimes found small quantities of alcohol in fruits and 

 other vegetable organs, surrounded with ordinary air, but always in small 

 proportion, and in a manner which suggested its accidental character. It 

 is easy to understand how, in the thickness of certain fruits, certain parts 

 of those fruits might be deprived of air, under which circumstances they 

 would have been acting under conditions similar to those under which 

 fruits act when wholly immersed in carbonic acid gas. Moreover, it would 

 be useful to determine whether alcohol is not a normal product of vegetatio*. 



