4 Transactions of the ee 
Plate LV., Figs. 3 and 4. Some yeast cells, however, as might be 
expected, were found in the sample to which the malt albumen 
that had been precipitated by alcohol was added, and it was found 
to contain a larger percentage of alcohol than any other of the 
albuminous samples. 
The experiments in the case of the malt were carried a little 
farther. Cane sugar was added to the malt extract from which the 
albumen had been separated by heating, and although the liquid in 
a short time afterwards was alive with minute creatures, the sugar 
was not converted into mucilage, and in the course of a few days 
natural fermentation set in. 
The extract of malt from which the albumen had been precipi- 
tated by alcohol was also operated upon. When the precipitated 
albumen had been separated by filtration, the alcohol contained in 
the filtrate was removed by distillation, and to the residue about 
15 per cent. of cane sugar was added. On the fourth day fermen- 
tation set in, and the ferment produced was the purest and finest 
specimen that I have seen, and the sample was entirely free from 
microscopic animals, &c. 
In fact the animals and germs that escaped being carried down 
by the alcoholic precipitate appeared to have been subsequently 
destroyed by long boiling in distilling off the alcohol. At the end 
of ten days the sample contained 10°63 per cent. of alcohol, and 
only -18 per cent. of acid; so that, after all the manipulation 
through which the extract was put, the natural ferment produced 
possessed considerable powers, and which were still unexhausted. 
The various germs and organisms infesting grain are the most 
formidable enemies with which we have to contend in the fermenta- 
tion of grain extracts. If these once obtain possession of the field, 
and gain the ascendency, they materially interfere with the success 
of the fermentative process. 
A temperature of about 175° Fahr., at which grain extracts are 
usually prepared, is not sufficient to destroy the animals and germs ; 
their vitality may be suspended, but if the subsequent conditions are 
favourable to their growth, they become revivified. 
To determine the effect which boiling has upon the fermentation 
of a malt extract, a comparative experiment was made. An infusion 
of malt was prepared and kept for two hours and a half at a tem- 
perature between 170° and 180° Fahr. The extract was then di- 
vided into two portions, one of which was boiled for some time, and 
afterwards about 15 per cent. of glucose was added to each portion. © 
At the end of ten days the portion which had been boiled contained 
10°38 per cent. of alcohol and 0°27 per cent. of acid, while the 
ved wie 0:78 per cent. of acid and only 6°26 per cent. of 
alcohol. 
In the one case the yeast cells had had possession of the field 
