STUDIES ON FERMENTATION. 23 



sketch, which was taken on the spot (Fig. 1). It was evident 

 that the working of the porter was extremely unsatisfactory, 

 and had, perhaps, been so for a long time ; indeed, we weie told 

 that they had obtained a change of yeast from another London 

 brewery that same day. We made a point of examining this 

 yeast with the microscope. It was beyond comparison purer 

 than the preceding yeast. 



It is evident that if these brewers had been in the habit of 

 using the microscope they might have detected the unsoundness 

 of their produce before the time when they actuall}'^ made the 



a & 



®^ <© Q QUO 



Fig. 1. Fig. 2. 



discovery, which, no doubt, was forced upon them by the com- 

 plaints of their customers, or some other annoying circumstance, 

 that led to their obtaining a change of yeast. 



We next obtained permission to examine the yeast of the 

 other beers undergoing fermentation, especially those of white 

 beers, such as ale and pale ale. 



In the sketch which we made of these yeasts one may detect 

 the presence of the filaments peculiar to turned beer (Fig. 2). 



We examined with much interest the ales which had imme- 

 diately preceded those undergoing fermentation, the yeast of 

 which we had just inspected. We were furnished with two 

 kinds, both in casks, the one fined, the other not fined. The 

 latter was visibly turbid, and, examining a drop of it, we dis- 

 covered three or four filaments present in every field of tlie 

 microscope. The ale which had been fined was nearly clear, 

 but wanting in brilliancy ; it contained about one filament to the 

 field. We asserted in the presence of the head brewer, who 



