SCIENTIFIC RESEARCH IN PRACTICE. 273 



In the above we have only spoken of the brewing industry. 1 

 HANSEN'S discoveries have, however, already been applied to 

 other branches of industry in which alcoholic fermentation 

 plays a part. Thus experiments have been made at many 

 places in pressed-yeast factories and in distilleries, and in a 

 great number the system has already been introduced with 

 success. An important observation made by DELBRUECK and 

 others may be mentioned, viz., that an increase in the yield 

 of alcohol was often observed in distilleries in which pure 

 yeasts were used, without any considerably better attenuation. 

 This may be accounted for on the assumption that foreign 

 ferments which consume a part of the nutrient liquid, without 

 producing alcohol, are suppressed by the use of the absolutely 

 pure culture. 



In wine-fermentation a beginning was made, in 1888, by 

 a pupil of HANSEN'S, L. MARX, of Marseilles ; subsequently 

 other investigators have worked in the same direction in 

 France, MuELLER-THURGAU in Switzerland, FORTI and PICHI 

 in Italy, MACH and PORTELE in Austria, and WORTMANN in 

 Germany. NATHAN (Wurtemberg) and KAYSER (France) have 

 likewise made extensive experiments in connection with the 

 fermentation of fruit- wines. 



The author has had frequent occasion in the course of years 

 to point out to the industries concerned the advantages offered 

 by the use of selected types of yeast both in the manufacture 

 of grape-wine and in that of fruit- and berry-wine. A specially 



lr The " natural " pure culture of yeast or yeast-culture proposed by DEL- 

 BRUECK, which was to be performed in the breweries themselves in order to 

 free their yeast from wild yeast, is based simply on certain isolated observa- 

 tions, e.g. that certain wild yeast species in competition experiments were 

 observed to develop more freely at lower temperatures than the culture-yeasts 

 employed in the same experiments. It stands to reason, however, and has 

 been proved by experience, that no general rule can be formulated from such 

 detached observations. Neither is it possible by means of the processes 

 recommended by DELBRUECK, but known and used long before in breweries, 

 such as pumping the wort immediately after fermentation has begun into other 

 vessels, or pitching with the beer when the head forms on the surface at the 

 moment fermentation sets in (" Krausen "), to obtain certain results with regard 

 to the suppression of foreign ferments, still less in relation to the selection of 

 the best type of culture-yeast. Nor has DELBRUECK'S suggestion acquired any 

 practical significance as might have been foreseen. 



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