50 PURE CULTURES OF 



first place to test whether the cylinder is tight. To do this, 

 steam is cautiously introduced through k, whilst the other 

 cocks are closed ; water-pressure may also be employed. It 

 is evident that some care must be adopted, especially at first. 

 It is of importance that whoever is to use the apparatus shall 

 have previously made himself familiar with its construction 

 and use. The first trials are best made with water. The rule 

 should be made that one man only has charge of the appa- 

 ratus. Experience has shown me that especially at the 

 beginning this is often forgotten ; but when several are in 

 charge, matters do not work satisfactorily. 



Before the apparatus is set working it is necessary to 

 thoroughly sterilise the two cylinders, the pipe which unites 

 them, and also the pipe through which the wort passes on its 

 way to the wort cylinder. This is done by blowing a strong 

 current of steam through the whole. The filters are sterilised 

 as already mentioned in a sterilising oven. The fermenting 

 cylinder is sterilised by steam, admitted through one of the 

 cocks on the pipe k in Figs. 8 and 10. Whilst the high tension 

 steam is passing, the different cocks are opened from time to 

 time, so that it can escape through these as well as by the 

 bent tube c\ this operation takes half an hour. Shortly 

 before this the filter is screwed on, and then all the cocks are 

 closed except that on the bent tube. Simultaneously the 

 cock of the filter is opened in order that air may pass through 

 the filter g and the tube h into the cylinder. The latter cools 

 down as the air enters and the steam is gradually turned off. 

 In short, the cooling is effected by the current of air, which 

 mixed with the steam escapes through the bent tube c. So 

 long as a current of steam is seen to escape, the vessel of 

 water d is not required ; this is only required as an indicator 

 at a later period. If the steam were shut off suddenly, there 

 would be a danger of the filter not admitting a sufficient 

 volume of air to prevent a diminution of the pressure due to 

 cooling, and the result would be either that impure air would 



