RESEARCHES ON THE MANUFACTURE, 
26 
preparation, for researches on its effect on several carbohy¬ 
drates, which were carried out under the same conditions and 
at the same time as the above experiments with extracts of 
koji. The following trials were made : 
I. Cane sugar. 100 c.c. of sugar solution and 50 c.c. of 
yeast extract were digested at a temperature of 40-45°C for 6 
hours in closed bottles and examined with the polarimeter 
after cooling to 23°C. The rotations, degrees Wild, were 
found to be, as follows : 
Yeast extract, fresh.+ 1.6° 
,, ,, , after heating + 1.0°. 
Cane sugar solution.+ 12 9° 
Mixture, after heating — 2.4° 
The result at once distinctly proves that the yeast extrac 
effected the inversion of a considerable proportion of cane 
sugar. If the ferment applied had left the sugar unaltered, the 
rotation of the mixture would have amounted after heating to 
8.9°, while it actually diminished to—2.4°. Applying Landolt’s 
formula we ffnd that the whole cane sugar had undergone in¬ 
version by the ferment. 
IT. Milk sugar. In this experiment and in all the following 
the same kind and proportion of yeast extract was used as in 
the experiment on cane sugar just discribed and also applied 
in the corresponding trials on the effect of koji extract. 
The rotations were, as follows :— 
Milk sugar alone .12.7° 
Mixture, after heating. 9.0° 
If the yeast extract had not exerted any effect on the 
milk sugar, the rotation, after heating the mixture, would have 
been 8.8°, whereas 9.0° was actually observed. This slight 
difference lies within the ordinary limits of experimental errors 
and the experiment shows, that milk sugar is not acted on by 
yeast extract. 
