382 STUDIES ON FERMENTATION. 



ence that they will present in point of brightness. The wort 

 that was shaken up hot will have more colour, and will be 

 brilliant ; the other will be turbid, and will not become clear 

 for five or six days, when left to itself in contact with air and 

 filtered again. This explains a fact that may be easily verified 

 in practice : Boiled wort, if cooled down suddenly, or slowly 

 but out of contact with air, or shaken up cold in contact with 

 air, is opaque when filtered ; whilst the same wort, cooled 

 down on the coolers where it has taken a certain quantity of 

 oxygen into combination, generally passes through the filter 

 very bright. The intelligent brewer is uneasy when this is not 

 the case, for it cannot be denied that the easy clarification of 

 wort has a favourable influence on the easy clarification of 

 beer. 



It would, nevertheless, be a grave error to suppose that the 

 clarification of beer must necessarily folloAV that of wort, and 

 we may be permitted to make a digression here on the subject, 

 to prove this statement. 



On February 3rd, 1874, we brewed 2 hectolitres (44 gallons) of 

 beer. The boiling wort, hops and all, was run into a vessel like 

 that represented in Fig. 80, but provided in addition with a false 

 bottom, pierced with holes and fixed at 1 centimetre (0"39 

 inch) above the true bottom of the vessel ; this was meant to 

 retain the spent hops. The temperature of the wort in the vessel 

 after it was filled, February 3rd, 4 p.m., was 90° C. (194° F.), 

 that of the room was 10° C. (50° F.). We permitted the wort 

 to cool down gently, without running cold water over the 

 vessel. The wort indicated a density of 14° Balling. 



The following temperatures Avere taken : — 



