354 STUDIES ON FERMEXTATION. 



and wine do, as well as all the various natural or artificial worts 

 which serve to produce them. Thus it is evident that consider- 

 able care is necessary in subjecting wort and beer, whether in 

 course of manufacture or finished, to the action of atmospheric 

 air. If, therefore, it is a good thing to supply wort with 

 oxygen, as we have already pointed out, in order to facilitate 

 the fermentation and nourish the yeast, it is, on the other hand, 

 important that the quantity supplied to it should not be too. 

 great, otherwise we may injure the quality of the beer, and par-' 

 ticularly its fulness on the palate, that is its apparent strength, 

 which has very little to do with the proportion of alcohol in it. 

 The strength of a beer is intimately connected with those sub- 

 stances introduced by the hops into the wort and thus into the 

 beer, to which we previously alluded, and of which too little is 

 known ; their properties and the palatableness resulting from 

 them are very readily affected by the oxygen of the air.* 



We have, therefore, to ascertain the measure in which air 

 occurs during the process of brewing, and whether, in the 

 actual process, there may not be too great a proportion of active 

 oxygen present. The study of this subject requires that we 

 should know what quantities of oxygen may be held in solution 

 in the wort or absorbed by direct combination. Fortunately 

 this has been rendered a comparatively easy matter by a rapid 

 method of estimating the oxygen held in solution in liquids of 

 various kinds, devised by M. Schiitzenberger in 1872. As soon 

 as this method was made known, we requested M. E,aulin, 

 who was attached to our laboratory as assistant-director, to 

 apply it to the determination of oxygen in wort. This he did 

 with his accustomed skill, devising certain alterations of details 



* [It will be well for the reader to bear in mind, that the word 

 " strength," used by Pasteur many times in this chapter, has a different 

 meaning to that which attaches to it in the minds of English brewers, 

 who in nearly every case use it in reference to origival gravity, while the 

 author employs it, in this chapter, at any rate, to denote the palate 

 cltnracteristic of strength, in oih.Qv vfoxds paJnte-fulness. For this reason 

 wo have thought it best in many cases to actualh' substitute the term 

 " palate-fulness," or "body," for the littrai translation of the Frencti 

 word "force."— F. F.] 



