acid gas, we have come across a fact which corroborated those which we have already given in reference to the facility with which lactic and viscous ferments, and generally speaking, those which we have termed the disease ferments or beer, develop when deprived of air, and which shows, consequently, how very marked their aerobian character is.  If we immerse beet-roots or turnips in carbonic acid gas, we produce well-defined fermentations in those roots.  Their whole surface readily permits the escape of the highly acid liquids, and they become filled with lactic, viscous, and other ferments, This shows us the great danger which may result from the use of pits, in which the beet-roots are preserved, when the air is not renewed, and that the original oxygen is expelled by the vital processes of fungi or other deoxidizing chemical actions.  We nave directed the attention of the manufacturers of beet-root sugar to this point.]

In short, fermentation is a very general phenomenon.  It is life without air, or life without free oxygen, or, more generally still, it is the result of a chemical process accomplished on a fermentable substance capable of producing heat by its decomposition, in which process the entire heat used up is derived from a part of the heat that the decomposition of the fermentable substance sets free.  The class of fermentations properly so called, is, however, restricted by the small number of substances capable of decomposing with the production of heat, and at the same time of serving for the nourishment of lower forms of life, when deprived of the presence and action of air.  This, again, is a consequence of our theory, which is well worthy of notice,

The facts that we have just mentioned in reference to the formation of alcohol and carbonic acid in the substance of ripe fruits, under special conditions, and apart from the action of ferment, are already known to science.  They were discovered in 1869 by M. Lechartier, formerly a pupil in the Ecole Normale Superieure, and his coadjutor, M. Bellamy. [Footnote:  Lechartier and Bellamy, Comptes rendus de l’Academie des Sciences, vol. lxix., pp., 366 and 466, 1869.] In 1821, in a very remarkable work, especially when we consider the period when it appeared, Berard demonstrated several important propositions in connection with the maturation of fruits: 

I. All fruits, even those that are still green, and likewise even those that are exposed to the sun, absorb oxygen and set free an almost equal volume of carbonic acid gas.  This is a condition of their proper ripening.

II.  Ripe fruits placed in a limited atmosphere, after having absorbed all the oxygen and set free an almost equal volume of carbonic acid, continue to emit that gas in notable quantity, even when no bruise is to be seen—­“as though by a kind of fermentation,” as Berard actually observes—­and lose their saccharine particles, a circumstance which causes the fruits to appear more acid, although the actual weight of their acid may undergo no augmentation whatever.