1893 - 94 .] T)t 'KobQYtson on Fermentation of tSugars. 167 
3. Lactose. — In this sugar also the change seems to begin at 
once, but the after progress is slow, and never reaches a 
great amount ; the acid forming at the seventy-second hour 
only 0*2948 per cent. At the same period the solution of 
cane sugar contains 0*433 and dextrose 1*46 per cent, of 
butyric acid. 
4. Dextrose undergoes a slow fermentation until the end of the 
second day, when the further progress becomes greatly 
accelerated. 
5. Maltose suffers change to a greater extent up to the end of 
the fourth hour than any of the other sugars, with the 
exception of cane sugar. 
6. Lcemilose until the end of the fourth hour undergoes change, 
which runs somewhat equally with that of cane sugar. 
After this period, however, the production of butyric acid 
from Isevulose proceeds at a great rate, till, at the end of 
the second day, it far exceeds the amount produced from 
any of the other sugars. 
At the end of the second day the sugars may be arranged in the 
following order as regards the amount of change they undergo 
when acted on by the butyric ferment : — 
1. Lgevulose. 
2. Maltose. 
3. Dextrose. 
4. Invert Sugar. 
5. Cane Sugar. 
6. Lactose. 
III. Alcoholic Fermentation op Sugars. 
This was induced by adding 2 c.c. of fresh beer-yeast to each 
flask containing 100 c.c. of the 5 per cent, solutions of the sugars. 
The specific gravity was then taken, and all were kept at 38° C. 
for the following three days. At intervals during this period the 
specific gravity of each solution was taken, care being exercised 
to cool them down previously to 15° *5 C. 
The following table gives the results : — 
