STUPIES ON FERMENTATTOS. 



249 



(Fig. 62), liolding 4-7 litres (8^ pints), and fitted up like the 

 usual two-necked flasks, with the object of freeing the ferment- 

 able liquid from foreign germs, by boiling it to begin with, so 



Fig. 62. 



that we might carry on our work under conditions of purity. 

 The volume of yeast-water (containing 5 per cent, of sugar) was 

 only 200 c.c. (7 fl. oz.), and consequently, taking into account 

 the capacity of the flask, it formed but a very thin layer at the 

 bottom. On the day after impregnation the deposit of yeast 

 was already considerable, and forty-eight hours afterwards the 

 fermentation was completed. On the third day we collected 

 the yeast, after having analyzed the gas contained in the flask. 

 This analysis was easily accomplished by placing the flask in a 

 hot-water bath, whilst the end of the curved tube was plunged 

 under a cylinder of mercury. The gas contained 41*4 per cent, 

 of carbonic acid, and, after the absorption, the remaining air 

 contained — 



Oxygen . . . . . . . . 19 7 



Nitrogen 80-3 



1000 

 Taking into consideration the volume of the flask, this shows a 

 minimum of 50 c.c. (3"05 cub. in.) of oxygen to have been 



