PRODUCED BY ALCOHOLIC FERMENTS. 225 



C was pitched with 400 grams of Carlsberg bottom yeast No. I. 



D 38o No. i, 



and 20 grams of Carlsberg bottom yeast No. 2. 



E 400 grams of Carlsberg bottom yeast No. 2. 



F 38o No. 2, 



and 20 grams of Carlsberg bottom yeast No. I. 



Whilst in the second series of experiments the ratio between the two 

 species in the mixture of yeasts was 9 : i, in this case it was 19 : i ; 

 otherwise the conditions were the same. The primary fermentation was 

 finished at the end of eleven days, when it was found that the extract was 

 7-31 per cent. Balling in ,7-64 per cent, in D, 7-39 per cent, in E and 

 7*64 per cent, in F. The clarification in C and D was rather unsatis- 

 factory, but was good in E and F. D was, perhaps, a little worse than 

 C, and E was a little better than F. In accordance with the previous 

 series of experiments, the attenuation in D was slightly less than in C, and 

 in F slightly less than in E. The conditions of storage were the same 

 as in the last series. 



After if months a considerable number of bottles were filled with 

 the beer from one series of the casks. The beer was bright in all 

 cases; its extract was 6*58 per cent. Balling in C, 6*90 per cent, in D, 

 6-25 percent, in E, and 6-33 per cent, in F. After standing fourteen 

 days in bottle C and E showed a very slight sediment, which, however, 

 on agitation, did not cloud the beer ; in D and F, on the other hand, 

 there was a more pronounced sediment, which, on agitation, rendered 

 the beer slightly cloudy. Thus, in this series of experiments there was 

 also an appreciable difference in the stability of the beer which had been 

 fermented, on the one hand, with pure cultures of either of the two brewery 

 yeasts, and on the other hand with the mixed yeasts. After about three 

 months' storage the beer of the second series of casks was drawn off into 

 bottles. The extract was found to be 6 '17 per cent. Balling in C, 6*33 

 per cent, in D, 6*25 per cent, in E, and 6*33 per cent, in F. In all cases 

 the beer was perfectly bright and stable, the only difference as regards 

 stability being that the beer from D became very slightly cloudy on agita- 

 tion, which was not the case with the others j there was, however, no 

 question of yeast turbidity. 



The addition of a low-fermentation yeast to ordinary lager 

 beer, at the stage when it is removed to the lager cellar, 

 had no injurious effect on the stability of the beer ; this also 

 holds good when the addition is made, after storage, to the 

 beer in the small casks and bottles. These experiments 

 were carried out in the same manner as those described 

 above. In all cases the normal, favourable conditions of the 

 brewery have been maintained. 



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