SYSTEMATICALLY SELECTED YEASTS. 41 



sufficient to confine oneself merely to outlines, but it is 

 necessary to elaborate the details ; many matters which in 

 theory appear trifles have in such a case a special importance. 

 In accordance with this, everything that is stated here is to 

 be regarded as the result of several years' experience and 

 trials in several breweries. 



In the following, the form of apparatus which is first 

 described is that in which neither the fermenting cylinder 

 nor the wort cylinder is provided with water-caps. The 

 former cylinder is covered with an insulating material such 

 as wooden' laths. In this form it is intended to be fitted up 

 in the fermenting cellar. The construction of the apparatus 

 is next described when intended to be placed in a room 

 above ground or under conditions which necessitate the 

 regulation of the temperature of the fermenting cylinder. 

 Finally instructions are given for using the apparatus. 



As shown in Fig. 8, the apparatus consists of three main 

 portions and the connecting tubes, namely : (i) the air pump 

 A for aerating the wort, and the air-holder B ; (2) the 

 fermenting cylinder C ; and (3) the wort cylinder D. 



The pump A is driven by machinery and draws the air 

 through a filter in order to effect a preliminary purification. 

 The air-holder B is provided with a pressure-gauge and a 

 safety valve. It is charged with air under a pressure of 1-4 

 atmospheres. The pipes must be fitted with cocks at suit- 

 able points for removing the water which collects in them. 

 This is of especial importance in the case of the pipe between 

 the air-holder B and the filters g and m. These are best 

 united by metal tubes with the air pipes. If rubber is 

 employed for this purpose, it must be very strong in order 

 to withstand the pressure. If metal tubes are used, they 

 should naturally possess some degree of elasticity and m.ust 

 be so arranged that the filters can be readily fitted and 

 disconnected. 



At the side of the fermenting cylinder C are two windows 



