PURE CULTURES IN T PRACTICE. 417 



cylinder ; an appliance (b, b) for stirring up the deposited yeast, 

 and a specially constructed cock (I) for drawing off the beer 

 and the yeast. At about the middle of the cylinder there is 

 a small side tube (j), fitted with india-rubber connection, 

 pinch-cock, and glass-stopper. When a portion of the wort 

 has been forced into the fermenting- vessel, the absolutely pure 

 yeast which is forwarded to the brewery in a flask specially 

 constructed for this purpose is introduced through the rubber 

 tube at j ; this is again closed, and the remainder of the wort 

 may then be added either at once or after the lapse of a few 

 days, according to the quantity of yeast introduced. 



Where it is necessary to regulate the temperature during 

 fermentation, the fermenting- vessel is surrounded by a water- 

 jacket. 



By means of this simple apparatus it is possible to obtain, 

 at short intervals, absolutely pure pitching yeast, sufficient 

 for about eight hectolitres of wort, and when once started the 

 apparatus works continuously. 



Another type of propagating apparatus has been described 

 by Bergh and Jorgensen (Fig. 99). The filtered air passes 

 through the three-way cocks at A, B, and C, into the two 

 cylinders A and" B. The upper cylinder holds about 50, the 

 lower cylinder 160 litres. A is provided with a stirrer E, 

 and a tube (a) for introducing the yeast and withdrawing 

 samples. The bent tube F is an outlet for carbon dioxide. 

 The tube G P connects the two cylinders, and the connection 

 can be made or broken by means of the cock O. H is the 

 outlet for water used in cleaning A. 



The cylinder B is surrounded by a cast-iron jacket made in 

 two parts ; the upper portion serves as a water-jacket for 

 cooling the wort and for regulating the fermentation ; the 

 lower portion is used as a steam-jacket, and is provided with a 

 cock at O as an inlet for the steam, and another at 8 as an 

 outlet. M is a ring-shaped tube provided with small holes ; 

 this is connected with the cold-water main during the cooling 

 of the wort ; the water is drawn off at N. The stirrer J is 

 set in motion by means of toothed gear. The height of the 

 liquid in the cylinder is indicated by means of a float, with 

 pointer and arc L. A bent tube, K, projects from the top of 



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