SYSTEMATICALLY SELECTED YEASTS. 47 



meter there is a tubular aperture through the jacket and 

 the side of the cylinder. The jacket is provided with a tap 

 near the bottom, forming the inlet for the cold water, and 

 another near the top and on the opposite side for its exit ; a 

 third tap at the bottom serves for removing the sediment 

 which is gradually deposited by the water. 



The wort cylinder (Fig. 10, D) is here also provided with 

 a jacket, which, however, can very well be omitted as the 

 perforated ring (Fig. 8, p) serves the same purpose suffi- 

 ciently well. Nevertheless the jacket has the advantage 

 that it encloses the water from the ring so that the operator 

 is not liable to be splashed. It adds, however, considerably 

 to the cost of the cylinder, and it makes it less simple to 

 manipulate. 



In Fig. 10, C, x, is shown 

 an improved, and therefore 

 also a somewhat more costly 

 construction of the cover than 

 that represented in Fig. 8. 

 The middle portion is made 

 of copper and is provided 

 with a brass flange with 

 twelve bolt holes. Between 



the cover and the collar of the cylinder a rubber washer 

 is inserted and fits into a groove ; a perfectly air-tight 

 joint is thus ensured. 



The letters in Fig. 10 otherwise correspond with those in 

 Fig. 8, and the above description therefore applies to both. 



The arrangement of the stirrer is seen better in Fig. 10 

 than in Fig. 8. In order to prevent its being raised out of 

 its bed at the bottom of the cylinder whilst in use, a ball- 

 socket is provided. As shown in Fig. 1 1 the axis ends in a 

 ball which rests in a hemispherical socket, and two pieces 

 accurately fitting the upper portion of the ball are bolted on ; 

 the axis can be rotated but cannot be raised from its socket. 



