122 
to the humbler electricity of glass and 
amber. Everywhere the growth of natural 
knowledge revealed always more and more 
of natural law. Magic and mystery in the 
greater part of the macrocosm and micro- 
cosm were no more. Alchemy, the philos- 
Ophers’ stone and the transmutation of 
metals were gone forever. Yet even as 
late as 1835 there still remained one large 
group of familiar natural phenomena which 
was neither understood nor explained. 
Fermentation, and especially alcoholic fer- 
mentation, had long excited the wonder of 
the ignorant, the curiosity of the wise. 
Fermentation was obviously the seat of 
active, spontaneous, self-regulated change. 
Its bubbling had given to it the name, 
which comes from the Latin fervere, to boil. 
Yeast was the constant accompaniment of 
the alcoholic fermentation, but exactly 
what yeast was no one knew. At best it 
seemed to be a consequence rather than a 
cause of fermentation, since it was more 
abundant at the end than at the beginning, 
more abundant in the later and less active 
stages than in the earlier and more active. 
Leeuwenhoeck indeed had examined yeast 
microscopically and found in it what 
seemed to be living cells, but his discovery 
appears to have occasioned no great sur- 
prise and to have been virtually forgotten 
after the lapse of a hundred and fifty years. 
The bubbling or boiling of the alcoholic 
fermentation suggested the action of acid 
on limestone, but as there was no limestone 
present and very little acid the suggestion 
explained nothing and was not very help- 
ful. Chemistry had dealt with the alco- 
holic fermentation, and had come to the 
conclusion, based upon analyses and ex- 
periments, that it was a purely chemical 
process, in which sugar was decomposed 
wholly into alcohol and earbonie acid, the 
cause of the decomposition being the ag- 
_ gressive action of the oxygen of the air. 
These were the days in which oxygen 
SOCLENOE. 
[N. S. Von. XIII. No. 317. 
was much in fashion, for it had been only 
recently discovered by Priestley in 1774, 
and it was perhaps natural that Gay 
Lussae, reflecting upon the successful ex- 
periments by Appert in preserving foods by 
canning, should have concluded that it was 
the exclusion of the atmospheric oxygen 
from the tins which prevented fermenta- 
tion of the fruit juices which they con- 
tained. He was confirmed in this opinion 
by his own experiment upon grape juice in 
the Torricellian vacuum, and his theory 
was, naturally enough, accepted and ex- 
tended by his pupil Liebig. There were 
not wanting, however, objectors to this. 
theory, nor experiments which seemed to. 
disprove it, and it was never very satis- 
factory because it failed to account ade- 
quately, not only for the constant presence 
and growth of yeast—for which no pro- 
vision was made in Gay Lussac’s formula, 
—bnut also because of the total absence of 
oxygen in the most active stages of alco- 
holic fermentation as conducted in brew- 
eries, etc. For most persons, therefore, 
fermentation was still an unsolved problem 
when, in 1836, Schulze completely dis- 
proved the oxygen theory by showing that 
ordinary air, such as had been excluded in 
the experiments of. Appert and Gay Lussac, 
was unable, even if admitted, to produce 
fermentation if it had first been caused to 
bubble slowly through concentrated sul- 
phuric acid which, whatever else it might 
do, certainly could not deprive it of oxygen. 
Putrefaction was another unsolved prob- 
lem in nature, not only at the beginning 
of this century, but as late as 1835, It 
obviously resembled fermentation in some 
respects, and had often been classified with 
it, but yet it was also obviously different. 
Bubbling was not always an accompani- 
ment of it, and the microscopes of the day, 
comparatively poor as they were, had re- 
vealed the almost constant presence in 
putrefactions of swarms of microscopic 
