104 PRACTICAL EXAMINATION OF BEER 



tions, to which from their character they also belong. But 

 as their publication was delayed until 1888 on account of 

 some other work, this was also the case with the investigations 

 under discussion. Their utility, however, is still the same as 

 at the time when they were made, for the question, as stated 

 above, is still awaiting its solution. 



When a brewer takes his samples of beer in the lager 

 cellar, his object is to ascertain not only its present condition, 

 but also how it will be after it has stood for a certain length 

 of time. His examination is a purely practical one, and he 

 does not avail himself of any scientific methods. The taste, 

 odour, colour and brightness of the beer are noted. Samples 

 are drawn off into clean bottles of colourless glass, which are 

 then well corked, and in order to ascertain how long the beer 

 will keep, these are set aside in a dark cupboard at the 

 ordinary room-temperature. It is then noted whether the beer 

 remains bright and unchanged in colour, and what length of 

 time elapses before an appreciable sediment has formed ; and 

 further, the appearance of the sediment, whether on shaking 

 it becomes readily diffused through the liquid, rendering the 

 latter cloudy or turbid, or whether it forms flocks, which again 

 soon sink to the bottom without appreciably affecting the 

 brightness of the beer. These changes are to be attributed to 

 the action of micro-organisms. If the beer gradually becomes 

 cloudy and discoloured without being shaken, there is bac- 

 terial disease. This, however, seldom occurs, and is a very rare 

 occurrence in well-conducted low-fermentation breweries. On 

 the other hand, a yeast sediment forms in the best beer after a 

 longer or shorter time, and consists partly of culture yeast, 

 partly of wild yeasts, and species are often present which 

 produce diseases e. g. yeast turbidity and disastrous changes 

 in the flavour. As stated, a yeast sediment will form in a vari- 

 able length of time, according to the culture yeast employed 

 and the degree of contamination with wild yeast. In the 

 following the term stability has reference merely to the yeast 



