Alcoholic fermentation / by Arthur Harden.

  • Arthur Harden
Date:
1932
Catalogue details

Licence: In copyright

Credit: Alcoholic fermentation / by Arthur Harden. Source: Wellcome Collection.

    39/258 page 29
    figure, according to a modification introduced by S. G. Paine, by a specially constructed bottle provided with two tubulures near the bottom. This ensures that no change in the pressure in the flask occurs, and the volume of gas observed is reduced to normal pressure by means of a table. Before making a reading it is necessary to shake the fermenting mixture thoroughly, as the albuminous liquid very readily becomes greatly supersaturated with carbon dioxide, so much so in fact that very little gas is evolved in the intervals between the shakings. The exact procedure in making an observation consists in shaking the flask thoroughly, replacing in the thermostat, allowing to remain for one minute, and then reading the level of the mercury in the azotometer. After the required time, say five minutes, has elapsed from the time at which the flask was first shaken, it is again removed from the bath, shaken as before, replaced, allowed to remain for one minute and the reading then taken. In this way readings can be conveniently made at intervals of three or five minutes or even less, and much more detailed information obtained about the course of the reaction than is possible by means of observations made at intervals of several hours. This apparatus can be constructed on a small scale so that observa- tions can be made with a total volume of 2 c.c. of fermenting liquid. A micro-apparatus has also been employed by Euler and Myrback [see Oppenheimer and Pincussen, 1929, p. 1297] which consists of a short test-tube in which the fermenting mixture is placed, connected by a capillary tube with a gas burette provided with a movable reservoir. The test-tube is completely immersed in the water of the thermostat and mechanically shaken throughout the experiment. The gas is collected under slightly diminished pressure and is brought to atmospheric pressure before being read. Another form of volumetric apparatus, designed by Walton [1904], has been used by Lebedev [1909], and a number of others have been described [see Dann and Quastel, 1928, Nord and Franke, 1928]. An apparatus on a different principle has been designed by Slator [1906] for use with living yeast, but is equally applicable to yeast- juice, and a very similar form has been more recently employed by Ivanov [1909, 2]. In this apparatus the change of pressure produced by the evolution of carbon dioxide is measured at constant volume, and comparative rates of evolution can be obtained with considerable accuracy, although the method has the disadvantage that the absolute volume of gas evolved is not measured. The apparatus consists of a bottle or flask connected with a mercury manometer. The fermenting
    digitised image 1
    digitised image 2
    digitised image 3