In passing it is of interest to note how promptly the preceding results were turned to good account practically. In well-managed distilleries, the custom of aerating the wort and the juices, to render them more adapted to fermentation, has been introduced. The molasses, mixed with water, is permitted to run in thin threads through the air at the moment when the yeast is added. Manufactories have been erected, in which the manufacture of yeast is almost exclusively carried on. The saccharine worts, after the addition of yeast, are left to themselves, in contact with air, in shallow vats of large superficial area, realizing thus on an immense scale the conditions of the experiments which we undertook in 1861, and which we have already described in determining the rapid and easy multiplication of yeast in contact with air. The next experiment attempted was to determine the volume of oxygen absorbed by a known quantity of yeast, the yeast living in contact with air, and under such conditions that the absorption of air was comparatively easy and abundant. [Illustration: Fig. 65.] With this object we repeated the experiment that we performed with the large-bottomed flask (Fig. 62), employing a vessel shaped like Fig. B. (Fig. 65), which is, in point of fact, the flask A with its neck drawn out and closed in a flame, after the introduction of a thin layer of some saccharine juice impregnated with a trace of pure yeast. The following are the data and results of an experiment of this kind. We employed 60 c.c. (about 2 fluid ounces) of yeast-water, sweetened with 2 per cent. of sugar and impregnated with a trace of yeast. After having subjected our vessel to a temperature of 25° C. (77° F.) in an oven for fifteen hours, the drawn-out point was brought under an inverted jar filled with mercury and the point broken off. A portion of the gas escaped and was collected in the jar. For 25 c.c. of this gas we found, after absorption by potash, 20·6, and after absorption by pyrogallic acid, 17·3. Taking into account the volume which remained free in the flask, which held 315 c.c., there was a total absorption of 14·5 c.c. (0·88 cub. in.) of oxygen.[118] The weight of yeast, in a state of dryness, was 0·035 gramme. It follows that in the production of 35 milligrammes (0·524 grain) of yeast there was an absorption of 14 or 15 c.c. (about 7/8 cubic inch) of oxygen, even supposing that the yeast was formed entirely under the influence of that gas: this is equivalent to not less than 414 c.c. for 1 gramme of yeast (or about 33 cubic inches for every 20 grains).[119] Such is the large volume of oxygen necessary for the development of one gramme of yeast when the plant can assimilate this gas after the manner of an ordinary fungus.