150 MICRO-ORGANISMS AND FERMENTATION. 



Alcohol. Glycerine. 

 Maximum ... ... 100 5'497 



Minimum 100 4-140 



whilst the Carlsberg beers gave the following numbers : 

 No. 1. No. 2. 



Alcohol. Glycerine. Alcohol. Glycerine. 



100 2-63 100 3-24 



It is thus seen, that, as Borgmann also points out, 

 good beer may be produced in which the ratio of glycerine 

 to alcohol is lower than the previously-admitted minimum. 

 A series of eight different species of Saccharomyces, and 

 amongst them six " cultivated " yeasts, all in absolutely pure 

 cultures, were investigated by Amthor with reference to their 

 chemical action on beer-wort. His results again confirmed 

 Hansen's principle, that in practice a selection must always 

 be made. The fermentations were conducted in Pasteur 

 flasks of one liter capacity under the same conditions and 

 in two series, the first of which corresponded to the primary 

 fermentation in the brewery, and the second at the same 

 time also to the secondary fermentation. The alcohol, 

 extract, specific gravity, attenuation, glycerine, nitrogen, 

 reducing substance, and the degree of colour, were deter- 

 mined in the fermented worts. The tables show, as pointed 

 out by the author, palpable differences in the work accom- 

 plished by the different species. The percentage of alcohol 

 (by volume) varied within the limits 4-34 and 6'02 (3-55 

 to 5*94 at the end of the primary fermentation), the extract 

 between 8-27 and 11-23 (8'49 to 12-61 at end of primary 

 fermentation), the attenuation between 36*7 and 53-3 (28-8 

 to 52-1 at eod of primary fermentation) ; the percentage of 

 glycerine showed very striking differences and fluctuated 

 between 0*08 and 0'15 ; and likewise the amounts of nitrogen 

 and reducing substance, and to some extent also the degree of 

 colour, showed considerable differences. 



A very considerable number of Saccharomycetes occurring 



