PRODUCED BY ALCOHOLIC FERMENTS. 193 



the brewery it is evident that the greatest care and precau- 

 tions must be taken ; only then can they be undertaken 

 without incurring danger. 



IV. Series of Experiments. Three fermenting vessels, A, B and C, 

 were fitted up in the fermenting cellar mentioned above ; they were made 

 of wood, and their form was that of the ordinary fermenting vessels. Into 

 each of these i^ hectoliters of wort (14 per cent. Balling) were introduced. 



A was pitched with 400 grams of Carlsberg bottom yeast No. 2. 



B 350 No. 2, 



and 50 grams of Sacch. Pastorianus III. 



C 350 grams of Carlsberg bottom yeast No. 2, 



and 50 grams of Sacch. ellipsoideus II. 



The temperature of the wort was 7*5 C. at pitching. After eight 

 days the extract was 8 '13 per cent, in A, 8 '21 per cent, in B, and 8^29 

 per cent. Ball, in C. As regards brightness, A was good, and B and C 

 only moderately good. The beer from each vessel was drawn off into 

 two similar casks, which were then placed in a lager cellar at a tempera- 

 ture of 0-5-2 -5 C. 



After the beer had remained in the cellar for about a month, it was in 

 each case bright, and had the appearance and taste of a good normal 

 beer such as occurs in commerce. A considerable number of bottles 

 were filled from each cask, and these were set aside in a dark cupboard 

 at the ordinary room-temperature. After eight days the beer from A was 

 still bright and without appreciable sediment, whilst the beers from B 

 and C had developed a fairly pronounced sediment, which on agitation 

 rendered the beer cloudy. The species of brewery yeast employed in 

 this experiment is one which gives a beer which is bright after short 

 storage, and has a full taste, but only a moderate degree of stability. 

 After it had been twelve days in bottle, the beer from A also began to 

 show a distinct sediment ; in B and C, however, the sediment was much 

 more strongly developed. 



The same result was in the main obtained from a similar experiment 

 with Carlsberg bottom yeast No. i and the two disease yeasts, but in this 

 case the storage was carried on for a month longer. As in some earlier 

 experiments, it was found that the beer which had been fermented with 

 this yeast possessed much greater stability than that fermented with the 

 Carlsberg bottom yeast No. 2. 



As was to be expected, the two species of wild yeast 

 likewise produced the disease when the fermentation was 

 conducted in the brewery and under the ordinary conditions : 

 Sacch. ellipsoideus II. proved to be the more dangerous of the 

 two species. 



