190 "DISEASES" OF BEER, 



diseases here in question, but also of other diseases, care 

 was naturally taken that the fermentations of each series 

 were conducted in all respects under the same conditions, 

 except as regards the composition of the pitching yeast, upon 

 the action of which the whole question turned. Absolutely 

 pure cultures were also, of course, always employed. 



A considerable number of experiments, modified in various 

 ways, were made in the laboratory in connection with the 

 question of yeast turbidity, and especially with other yeasts 

 in addition to that mentioned from the Tuborg brewery. 

 The result was the same. On extending the investigation, 

 I obtained the interesting result that the two disease yeasts 

 did not produce the malady when they were only added to the 

 beer at tJie end of the primary fermentation , that is, at tJie stage 

 when storage commences. 



These experiments were now repeated on a larger scale. 

 The problem was the same as before, but I also wished to 

 determine what proportion of disease yeast must be present 

 in the pitching yeast in order to produce the disease, and 

 finally, what will be the effect of a lower or higher attenuation 

 during the primary fermentation, and also of a shorter or 

 longer period of storage. The following will serve as ex- 

 amples of the experiments which I undertook with a view 

 to the solution of these questions. 



II. Series of Experiments. Two Pasteur fermenting vessels, A and 

 B, were charged, each with 165 liters of aerated wort (13-5 per cent. 

 Ball.) such as is employed in the brewery for the production of ordinary 

 lager beer. A was pitched with 660 grams of thick beer yeast, the 

 species used being the one which I subsequently described under the 

 name Carlsberg Bottom Yeast No. \ ; the second vessel, B, was pitched 

 with 644 grams of the same yeast, with the ( addition of 16 grams of 

 Sacch. ellipsoideus II. of the same thick consistency. The growths of 

 both yeasts were young and vigorous, and were produced under the same 

 conditions. The temperature of the wort when the yeast was added was 

 7 C, and the temperature of the room was 7- 10 C. during the primary 

 fermentation. After eight days the extract in A was 7 6, and in B 7 5 per 

 cent. Ball. From each fermenting vessel a cask of 66 liters capacity was then 

 filled, and these were placed in the lager cellar, the temperature of which 



