Studies on fermentation : the diseases of beer, their causes, and the means of preventing them . some of the liquid in the funnelentered the flask, carrying with it the small deposit of yeast. STUDIES ON FERMENTATION. 239 which was sufficient to impregnate the saccharine liquid con-tained in the flask. In this manner it is possible to introduceas small a quantity of yeast as we wish, a quantity the weightof which, we may say, is hardly appreciable. The yeast sownmultiplies rapidly and produces fermentation, the carbonic acidgas from which is expelled into the mercury. In less thantwelve days a
Studies on fermentation : the diseases of beer, their causes, and the means of preventing them . some of the liquid in the funnelentered the flask, carrying with it the small deposit of yeast. STUDIES ON FERMENTATION. 239 which was sufficient to impregnate the saccharine liquid con-tained in the flask. In this manner it is possible to introduceas small a quantity of yeast as we wish, a quantity the weightof which, we may say, is hardly appreciable. The yeast sownmultiplies rapidly and produces fermentation, the carbonic acidgas from which is expelled into the mercury. In less thantwelve days all the sugar had disappeared, and the fermentationhad finished. There was a sensible deposit of yeast adheringto the sides of the flask ; collected and dried it weighed 2*25grammes (34 grains). It is evident that in this experiment thetotal amount of yeast formed, if it required oxygen to enable itto live, could not have absorbed, at most, more than the volumewhich was originally held in solution in the saccharine liquid,when that was exposed to the air before being introduced intothe Fig. 59. Some exact experiments conducted by M. Raulin in ourlaboratory have established the fact that saccharine worts, likewater, soon become saturated when shaken briskly with an B40 STUDIES ON FERMENTATION. excess of air, and also that they always take into solution a littleless air than saturated pure water contains under the same con-ditions of temperature and pressure. At a temperature of 25° C.(77° F.) therefore, if we adopt the coefficient of the solubility ofoxygen in water given in Bunsens tables, we find that 1 litre(If pints) of water saturated with air contains 55 (03 cubicinch) of oxygen. The three litres of yeast-water in the flask,supposing it to have been saturated, contained less than (1 cubic inch) of oxygen, or, in weight, less than 23 milli-grammes (035 grains). This was the maximum amount ofoxygen, supposing the greatest possible quantity to have been
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