120 t METHODS OF STERILISATION. 



abolish the cooler and to effect the rapid cooling of the wort (as 

 well as its aeration by the injection of germ-free air) in closed 

 vessels fitted with refrigerating appliances, are thus easily accounted 

 for. This method of procedure, which, from the fermentation 

 physiologist's point of view, is the only correct one, is, however, 

 beset with a difficulty as regards the separation of the sedimentary 

 matter. Therefore the hot wort from the copper is generally 

 allowed to stand until the sediment has subsided, the still hot goods 

 being then carefully drawn off and conveyed to suitable cooling 

 and aerating apparatus. For a description of the latter, reference 

 must be made to Handbooks on Brewing, three of which are 

 recommended : that of THAUSING (I.) studies the wants of the 

 practical brewer; whilst MORITZ and MORRIS'S (I.) work is in- 

 tended for the brewing chemist familiar with chemistry and 

 micro-biology, to whom it presents a large amount of lucid in- 

 formation. These two books being supplementary one to the 

 other, the student will do well to leave neither unread. Finally, 

 the third work, C. J. LINTNER'S (I.) Handbuch der landwirtschaft- 

 lidien Gewerbe, is adapted for imparting instruction in High 

 Schools. 



The sterilisation of wort in Pasteur flasks the medium most 

 frequently employed in the fermentation physiologist's laboratory 

 will be briefly described as an addendum to the preceding 

 remarks. In order to produce a clear liquid, poor in precipitated 

 albuminoids, &c., the Pasteur flask is half filled with wort (not 

 from the hop copper, but from the cooler), which will now contain 

 numerous germs, several hundreds to thousands per c.c. The 

 flask is then placed on a heated sand-bath and the steam evolved 

 is allowed to escape for ten minutes counting from the moment 

 boiling begins through the short caoutchouc tube on the lateral 

 tube of the flask, whereupon the former is closed by a glass stopper 

 previously purified in the flame. Then, for a further ten minutes, 

 the steam is allowed to escape through the swan-neck, and the 

 flask is left to cool, being for that purpose placed on a hollowed 

 cork or a ring of millboard one inch in height. When the liquid 

 has again sunk to the temperature of the room, the moisture con- 

 densed in the swan-neck is driven off by means of the gas-flame, 

 and the neck is closed by a small plug of asbestos which subse- 

 quently serves as a germ filter. Any organisms capable of passing 

 through this are deposited in the first bend of the tube, which is 

 then freed therefrom, by heating it to redness in the flame, before 

 proceeding to inoculation. Concerning the sterilisation of the 

 large copper apparatus for pure yeast culture, detailed instructions 

 have been given by E. CH. HANSEN (III.). 



