Studies on fermentation : the diseases of beer, their causes, and the means of preventing them . oy any germs adhering to the sides. When cold the liquidis impregnated by means of a trace of pure yeast, introducedthrough the glass-stoppered tube. If these precautions areneglected it is scarcely possible to secure a successful fermenta-tion in our flasks, because the yeast sown is immediately held incheck by a development of anaerobian vibrios. For greatersecurity, we may add to the fermentable liquid, at the momentwhen it is prepared, a very small quantity of tartaric acid,which will prevent t
Studies on fermentation : the diseases of beer, their causes, and the means of preventing them . oy any germs adhering to the sides. When cold the liquidis impregnated by means of a trace of pure yeast, introducedthrough the glass-stoppered tube. If these precautions areneglected it is scarcely possible to secure a successful fermenta-tion in our flasks, because the yeast sown is immediately held incheck by a development of anaerobian vibrios. For greatersecurity, we may add to the fermentable liquid, at the momentwhen it is prepared, a very small quantity of tartaric acid,which will prevent the development of but3ric vibrios. The variation of the ratio between the weight of the yeastand that of the sugar decomposed by it now claims special atten-tion. Side by side with the experiments which we have justdescribed, we conducted a third lot by means of the flask C STUPIES ON FERMENTATTOS. 249 (Fig. 62), liolding 4-7 litres (8^ pints), and fitted up like theusual two-necked flasks, with the object of freeing the ferment-able liquid from foreign germs, by boiling it to begin with, so. Fig. 62. that we might carry on our work under conditions of volume of yeast-water (containing 5 per cent, of sugar) wasonly 200 (7 fl. oz.), and consequently, taking into accountthe capacity of the flask, it formed but a very thin layer at thebottom. On the day after impregnation the deposit of yeastwas already considerable, and forty-eight hours afterwards thefermentation was completed. On the third day we collectedthe yeast, after having analyzed the gas contained in the analysis was easily accomplished by placing the flask in ahot-water bath, whilst the end of the curved tube was plungedunder a cylinder of mercury. The gas contained 41*4 per cent,of carbonic acid, and, after the absorption, the remaining aircontained— Oxygen . . . . 19 7 Nitrogen 80-3 1000Taking into consideration the volume of the flask, this shows aminimum of 50 (305 cub. in.) of oxy
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