ON BACTERIOLOGY IN ITS EELATIONS TO CHEMICAL SCIENCE. 445 



fermentation ' which is so essential to the ' conditioning ' of the beer. 

 Quite recently, however, this difficulty is said to have been overcome by 

 Van Laer, who has succeeded in obtaining a yeast in a state of purity 

 which is endowed with this power. 



In this connection it is worthy of remark that, during the past year, 

 there has been established, at Burton-on-Trent, ' The British Pure Yeast 

 Company,' under the direction of Dr. Van Laer, from which it is hoped 

 that the British breweries will be gradually induced to adopt the employ- 

 ment of pure yeast fermentations. 



In his last publication Hansen (' Untersuchungen a. d. Praxis der 

 Garungsindustrie,' Munich and Leipzig, 1892) gives a list of the various- 

 breweries in which his method has been adopted, and of which the- 

 following table is a summary : — 



Bkeweries using Hansen's Appaeatus. 

 (1) Bottom Fermentation. 



10 



13 



1 



1 



1 



Although in this table given by Hansen — he does not refer to any- 

 English breweries using his apparatus — he states that he believes there 

 are now one or two in which it is beginning to be regularly employed. 



Speaking of this country, Hansen says that English brewers were 

 more disposed to talk than to experiment, and, after referring to the for- 

 mation of the British Pure Teast Company, he remarks that ' there is 

 now a prospect of the new advance shortly taking root in the great conservative 

 island-empire ! ' 



As regards the mechanism of the alcoholic fermentation of sugar, the 

 ingenious theory of Pasteur, which ascribed it to the life of the yeast 

 organism in the absence of oxygen, has now been generally abandoned ; 

 in fact, the recent experiments of Adrian Brown conclusively show that 

 a given number of yeast-cells actually produce more alcohol when 

 abundantly supplied with oxygen than when this gas is excluded. It 

 has long been admitted that the vegetative activity of the yeast is 

 increased by the access of oxygen, and with this increased activity it& 

 specific power of decomposing sugar is heightened also. 



Of greater interest to the chemist than the ordinary alcoholic fer- 

 mentation are those numerous and much more divei'sified fermentative 



