280 GRAPE CULTURE AND 



the mash. The same quantity of mash, set without cover and 

 at the outset left without stirring (No, 557), was markedly 

 slower in its course, although the maximum temperature 

 reached was the same and occurred about the same time as 

 -in the other case. As the fermentation seemed nearly ended 

 on the evening of the third day, a floating cover was put on 

 in order to prevent acetification during the night, and the 

 hot chamber was opened so as to share the temperature of 

 the room, viz., 75. But in the morning a cap had formed 

 and a slight fermentation was still going on, as is evidenced 

 by the temperature having remained at 93, despite exposure 

 to a much lower one. But a few hours later all appearance 

 of fermentation vanished. It is not easy to see why the 

 absence of the cover should have made so much difference in 

 the time of ending the fermentation. Less frequent stirring 

 was probably the main cause. 



The relatively small mass concerned in these fermentations 

 prevented the temperature from rising so high as to injure the 

 yeast, 102 being the maximum observed. With the larger 

 masses used in the other experiments, the temperature rose as 

 much as 20 above that of the room ; and correspondingly 

 the maximum in these two fermentations would probably have 

 been about 120, had the same amount of grapes been used. 



In the two fermentations (Nos. 558 and 559) with frames 

 to keep the pomace submerged, the record shows that while 

 up to the time of the maximum, the temperature was always 

 highest at the top, shortly afterward this relation became in- 

 verted, the lower portion being found warmer than the 

 upper. This fact is most apparent in the case where the sin- 

 gle frame was used (No. 559), in which the maximum tem- 

 perature of the must below the pomace cap was actually 

 attained about thirty hours later than in the pomace itself, 

 showing that the fermentation in this lower portion was far 

 behind that in the upper. This consecutive occurrence of 



