STUDIES OX FERMENTATION. 243 



February 9th. To do this we poured oif the liquids in A and 

 B, collecting the j^easts on tared filters. Filtration was an 

 easy matter, more especially in the case of A. Examining the 

 yeasts under the microscope, immediately after decantation, we 

 found that both of them remained very pure. The yeast in A 

 was in little clusters, the globules of which were collected 

 together, and appeared by their well defined borders to be 

 ready for an easy revival in contact with air. 



As might have been expected, the liquid in the flask B 

 did not contain the least trace of sugar; that in the flask A 

 still contained some, as was evident from the non-completion of 

 fermentation, but not more than 4'6 grammes (71 grains). 

 Now, as each flask originally contained 3 litres of liquid, 

 holding in solution 5 per cent, of sugar, it follows that 150 

 grammes (2,310 grains) of sugar had fermented in the flask 

 B, and 145-4 grammes (2,239"2 grains) in the flask A, The 

 weights of yeast after drying at 100° C. (212° F.) were— 



For the flask B, with air . . 1'970 grammes (30'4 grains). 

 For the flask A, without air . . 1"368 grammes.* 



The proportions were 1 of yeast to 76 of fermented sugar in the 



first case, and 1 of yeast to 89 of fermented sugar in the second. 



From these facts the following consequences may be deduced : 



1. The fermentable liquid (flask B), which since it had been 

 In contact with air, necessarily held air In solution, although 

 not to the point of saturation, inasmuch as It had been once 

 boiled to free it from all foreign germs, furnished a weight 

 of yeast sensibly greater than that yielded by the liquid which 

 contained no air at all (flask A), or, at least, which could only 

 have contained an exceedingly minute quantity. 



2. This same slightly aerated fermentable liquid fermented 

 much more rapidly than the other. In eight or ten days it 

 contained no more sugar ; while the other, after twenty days, 

 still contained an appreciable quantity. 



Is this last fact to be explained by the greater quantity of 



* [This appears to be a misprint fori '638 grarames=25'3 grains. — D.C. E.] 



R 2 



