The soluble ferments and fermentation / J. Reynolds Green.

  • Joseph Reynolds Green
Date:
1901
Catalogue details

Licence: In copyright

Credit: The soluble ferments and fermentation / J. Reynolds Green. Source: Wellcome Collection.

    22/540 page 2
    Though many of the reactions thus grouped together were possessed of very little in common, one process which was of very early date was associated correctly with fermentation. This was the action of leaven in the preparation of bread. The evolution of gas was observed in connection with the raising of the dough, though no further resemblance to the alcoholic fermentation was recognised. Indeed the speculations con- cerning leaven and its action were of the wildest order, some writers comparing it to the hypothetical philosopher’s stone, and attributing to it the power of transforming the dough into something resembling itself. One fact of importance came out amidst all the mass of confusion, though its interpretation left much to be desired. This was the discovery that a very small quantity of leaven was capable of fermenting or transforming an almost indefinite amount of dough. The latter was however considered to be converted into leaven. Another point of resemblance between these two fermen- tative processes was known at a comparatively early date. Just as the aeration of dough was associated with the presence of leaven, alcoholic fermentation was found to be accompanied by the formation of a deposit in the fermenting liquid, which took the form sometimes of a sediment, sometimes of a scum floating on the surface. By many writers con- siderable importance was attached to this deposit, and, as in the case of the leaven, some special occult force was attributed to it, by virtue of which it set up the changes which could be observed in the liquid. It was consequently called a ferment. The true nature of this deposit, like that of leaven, for a very long period was not investigated, nor the part it plays at all understood. About the end of the sixteenth century the process of putrefaction was associated with the two fermentations so far mentioned, and the three shown to have much in common. The confusion however which led to the association of efferves- cence with them was maintained for some considerable time. It was not till 1659 that de la Boe pointed out that they differ considerably from effervescence, the chief reaction of
    digitised image 1
    digitised image 2
    digitised image 3