5oo 
Green . — The supposed 
limb of the manometer rose slightly, pointing to an absorption 
of some constituent of the air in the flask. 
Dr. Blackman was kind enough to measure for me, by 
means of his very delicate apparatus (described by him in the 
Phil. Trans. ( 3 )), the amount of C 0 2 that was being evolved 
by the fermenting liquid per hour in both of these experi- 
ments. The quantity varied very slightly from time to time, 
did not show a diminution pari passu with the diminution 
of the weight of the sugar-solution, and did not amount to 
more than -oi cc. per hour, which is not more than one-tenth 
of the quantity which would have been produced had the loss of 
weight of the sugar-solution been caused by the splitting 
of a corresponding amount of sugar into C 0 2 and alcohol. 
At the end of the experiment I examined the digestions for 
alcohol in the usual way, by neutralizing, distilling off two- 
thirds of the liquid, adding distilled water to make up the 
original bulk, and taking the specific gravity. After the ten 
days of the first experiment quoted, the liquid contained 
•2°/ 0 of alcohol. 
I may quote further a series of experiments I made to 
ascertain if alcohol was produced during the fermentations, 
and whether, if so, the quantity increased in any proportion 
to the duration of the digestion. 
I mixed 50 cc. of a freshly prepared Yeast-extract with 
100 cc. of a 40°/ o solution of glucose, and divided it into 
five equal parts, A, B, C, D, and E, which were set in an 
incubator at 29 0 C. in flasks fitted with gauges or mano- 
meters. Prior to starting the digestion A was boiled to serve 
as a control. It gave the usual bulky coagulum at 45 0 to 
50° C. The experiments were started on May 28, and the 
weight of a specific-gravity-bottle filled with the liquid was 
27-35° gms. One flask, C, was examined at intervals of 
twenty-four hours, and the weights obtained were the 
following : — 
May 31, 27-338 gms. 
June 1, 27-340 „ 
» 2, 27-338 „ 
