STUDIES ON FERMENTATION. 379 



same condition as when it comes on the coolers, was put into a 

 graduated, cylindrical vessel, which was then closed with an 

 india-rubber cork, and placed immediately, without being 

 shaken, in a hot water bath at 85° C. (185° F.). Another 

 vessel similar to the preceding one, and having a thermometer 

 passed through the cork, and immersed in the wort, enabled us 

 to observe the temperature. The temperature was gradually 

 reduced, in exact accordance with the data of the preceding 

 curve, until the water, in the course of eight hours and a half, 

 was brought down to 10° C. (50° F.). It is true, that we can- 

 not pretend to have realized all the conditions of the coolers, in 

 this manner, but we approached them very nearly ; moreover, 

 it was an approximation rather than a rigorous determination 

 that we desired to obtain. We then collected over mercury the 

 air which remained in the flask, and analyzed it very carefully ; 

 at the same time, with Schiitzenberger's apparatus, we deter- 

 mined the oxygen held in solution in the wort so treated. 

 From the results thus obtained we easil}^ found the quantity of 

 oxygen that had disappeared — that is, the oxygen which the 

 wort had acquired from the atmosphere of the flask, and which 

 had combined with the oxidizable matters of the wort. 



The volume of the flask being 815 c.c, that of the wort 

 391 CO., and the depth of the liquid 8 cm., we found an absorp- 

 tion by combination of 9'49 c.c. of oxygen per litre of wort 

 (2"63 cub. ins. per gallon). Another flask treated in the same 

 manner gave us similar results. 



As the oxygen in solution has so great an influence on fer- 

 mentation, it is important that we should, likewise, know the 

 efiect produced by the oxygen in combination. The following 

 considerations and experiments may throw some light on this 

 subject : — 



We have already remarked that natural saccharine worts 

 oxidize, and acquire colour in contact with air, and that this 

 coloration disappears when these worts are caused to ferment. 

 This furnishes one presumption, that the oxygen in combination 

 disappears then, from, being abstracted by the ferment. A 



