STUDIES ON FERMENTATION. 389 



vessel A. This vessel is made of tinned iron, or, better still, 

 tinned copper, and has a cover provided with a man-hole and 

 eye-hole ; m n is one of the tubes for the circulation of air 

 during fermentation ; its connecting-tube is not represented, it 

 would be behind the vessel. 



At the point d there is a pipe for admission of pure air ; 

 this is represented on a larger scale at T. The wort, as it runs 

 through the large tube, carries with it air from outside, and 

 this air is calcined on its way in by means of a flame which 

 plays on the copper tube through which it passes. This arrange- 

 ment supplies a third or more of the total quantity of oxygen 

 that the wort is capable of acquiring by solution at the tempe- 

 rature at which we work. 



r represents the arrangement of the reversed funnel in which 

 the tube m n terminates. Its mouth is closed with cotton- wool 

 held in place between two pieces of wire gauze, for the pur- 

 pose of purifying the air that enters by it into the fermenting 

 vessel during fermentation. 



V is an entrance tap for steam, by means of which the vessel and 

 refrigerator are cleansed from all extraneous germs before each 

 fermentation, and before the wort passes into the refrigerator. 



"When the fermenting vessel A is at work, we may start a 

 fermentation in a second vessel in the following manner : open- 

 ing a small tap situated at about a third of the height of the 

 vessel, we pass a few litres of the fermenting beer into a can of 

 tinned copper, previously purified b}^ a current of steam, and 

 filled with pure air. This can is then emptied into the fresh 

 vessel, an operation of no difiiculty, since we have merely to 

 connect the tap of the can with the small tap of the vessel, 

 and lastly, the vessel is filled with wort, which then mixes 

 with the fermenting liquid. These various manipulations, it 

 is evident, are performed under conditions of complete purity, 

 without the slightest contact of the liquids either with the ex- 

 terior air or with utensils contaminated by disturbing germs.* 



* This arrangement limits the proportion of oxygen that may be intro- 

 duced into the wort by direct oxidation. But it would be easy to 



