i88 "DISEASES" OF BEER, 



is, however, out of place in this chapter. Irregularities caused 

 by the brewery yeast itself, cannot be regarded as diseases, 

 at any rate not in the sense in which the word is here made 

 use of, and has hitherto been employed in the literature of 

 this subject. 



In the following pages are described my experiments on 

 the diseases caused by alcoholic ferments, as well as some 

 investigations which are related to this subject, In the 

 numerous experiments which this work involved I have been 

 assisted by Mr. Gram and Mr. Nielsen. 



Yeast Turbidity in Beer y caused by Sacch. ellipsoideus II. and 

 Sacch. Pastorianus III. 



When I commenced the study of this disease in 1882-83, 

 it was regarded as one of the most dreaded maladies, not 

 only in Denmark, but to a still greater extent in Germany ; 

 and it not infrequently caused great losses in low-fermenta- 

 tion breweries. As we have already seen, it was for a time 

 assumed that this disease was caused by a foreign yeast 

 fungus, Sacch. exiguus ; later, the cause was attributed to 

 the degeneration of ordinary brewery yeast, Sacch. cerevisice, 

 in that the latter developed only small light cells instead of 

 large heavy cells. 



In the Tuborg brewery at Copenhagen, this disease mani- 

 fested itself as follows : When, at the end of the storage 

 period, the beer was drawn off in the cold lager-cellars, it 

 was bright and faultless in appearance ; but after the casks 

 or bottles into which it had been drawn off had been exposed 

 for a few days to a warmer temperature than that of the 

 lager cellar, a more or less abundant yeast deposit had 

 formed, and, on slight agitation, rendered the beer cloudy. 

 When the malady was strongly developed, the beer became 

 so cloudy, only a few days after being drawn off from the 

 lager casks, that it was quite undrinkable. The experiments 



