STUDIES ON FERMENTATION. 393 



in its earliest stage. Now, comparing the relative unsoundness 

 of the two beers, we see that M kept at least two months 

 longer than the corresponding brewery beer. This example 

 shows us that as far as the keeping powers and the quality of 

 beer are concerned, the existing process would gain consi- 

 derably by the employment of pure wort and pure ferment ; 

 and, indeed, it seems likely that the new process may be intro- 

 duced into breweries with this object in view. 



In the course of the summer of 1875 we made the following 

 observations on the keeping qualities of a beer brewed on the 

 new system, all the details of which had been rigorously carried 

 out. The beer brewed at Tantonville during the months of 

 June and July, at a temperature of 13° C. (5 5 "4° F.), in 

 50-litre and 80-litre casks (11 and 18-gallon), had been sent by 

 slow trains to Arbois (Jura), where we were staying for a time. 

 The temperature of the wine cellars in which these barrels were 

 stored was, on June 1st, 125° C. (54*5° F.) ; this rose gradually 

 until September 1st, when it attained 18° C. (64-4° F.). la 

 this cellar the brewery beer, brewed in the ordinary way, 

 underwent change in the course of fifteen daj's or three weeks, 

 whilst the beer brewed on the new system remained sound for 

 several months. It is true that some of the barrels lost their 

 frothiness, and that the beer in them underwent a peculiar 

 vinous change, but these efiects in no way depend on the 

 conditions peculiar to the new process. 



Comparing the beers K, M, T, of which we have been 

 speaking, we see that, however useful the aeration and oxida- 

 tion of the wort may be in quickening fermentation and facili- 

 tating clarification, yet it is by no means indispensable to the 

 success of our operations that we should introduce into our 

 worts large quantities of oxygen, whether by solution or com- 

 bination. Beyond a certain limit — a limit which is undoubtedly 

 overstepped in the existing process — oxygen is injurious to the 

 palate characteristics and aroma of beer. 



These comparisons have proved to us that the new process 

 can be applied to wort aerated to the third of its saturate- 



