i;6 "DISEASES" OF BEER, 



necessary to effect sterilisation were made known by Pasteur's 

 predecessors ; and further, it was Pasteur and not Velten 

 who first made use of its technical application in the brewery. 

 The form of construction adopted by Velten is, moreover, in 

 several respects not to be recommended. It is evident that 

 these forms of apparatus acquire all their importance through 

 the yeast. If the yeast is not really a pure culture free from 

 all disease germs, they will be worthless. Since Pasteur's 

 yeast does not at all satisfy this requirement, it also follows 

 that the apparatus could not find any application in the 

 breweries. 



Nine years later their application for practical brewing 

 purposes was fully appreciated. As will be remembered, I 

 succeeded in 1883 in introducing the pure cultivation of a 

 systematically selected race, and when in the year following 

 this important reform was adopted in the Old Carlsberg 

 brewery and elsewhere, the impetus was given in the direc- 

 tion of the abolition of the open coolers. The apparatus 

 which was accordingly constructed in Carlsberg differed in 

 several respects from Velten's, and especially in the manner 

 in which the air is sterilised. Velten employed heat for this 

 purpose in accordance with Schwan's method ; in the Carls- 

 berg apparatus, on the other hand, the air is purified by means 

 of the cotton-wool filters of Schroder and Dusch, and this 

 method has proved to be much more practical. (Directions 

 for the purification of the air by means of cotton-wool filters, 

 and also a description of the pure yeast propagating apparatus 

 constructed by Captain Kiihle and myself, are given in the 

 earlier part of this book.) The employment of this apparatus 

 with my pure cultivated yeast has spread in recent years 

 over a large portion of the globe. As was to be expected, 

 the pure cultivation of systematically selected races had to be 

 first introduced. 



I have now discussed that portion of Pasteur's work which 

 bears directly upon the questions to be dealt with in this 



