A History of Science — Volume 4Williams, Henry Smith
History
A History of Science — Volume 4
Williams, Henry Smith
Science -- History
In a word, Pasteur showed that all the many familiar processes of the
decay of organic tissues are, in effect, forms of fermentation, and
would not take place at all except for the presence of the living
micro-organisms. A piece of meat, for example, suspended in an
atmosphere free from germs, will dry up gradually, without the slightest
sign of putrefaction, regardless of the temperature or other conditions
to which it may have been subjected. Let us witness one or two series of
these experiments as presented by Pasteur himself in one of his numerous
papers before the Academy of Sciences.
EXPERIMENTS WITH GRAPE SUGAR
"In the course of the discussion which took place before the Academy
upon the subject of the generation of ferments properly so-called, there
was a good deal said about that of wine, the oldest fermentation known.
On this account I decided to disprove the theory of M. Fremy by a
decisive experiment bearing solely upon the juice of grapes.
"I prepared forty flasks of a capacity of from two hundred and fifty to
three hundred cubic centimetres and filled them half full with filtered
grape-must, perfectly clear, and which, as is the case of all acidulated
liquids that have been boiled for a few seconds, remains uncontaminated
although the curved neck of the flask containing them remain constantly
open during several months or years.
"In a small quantity of water I washed a part of a bunch of grapes, the
grapes and the stalks together, and the stalks separately. This
washing was easily done by means of a small badger's-hair brush. The
washing-water collected the dust upon the surface of the grapes and the
stalks, and it was easily shown under the microscope that this water
held in suspension a multitude of minute organisms closely resembling
either fungoid spores, or those of alcoholic Yeast, or those of
Mycoderma vini, etc. This being done, ten of the forty flasks were
preserved for reference; in ten of the remainder, through the straight
tube attached to each, some drops of the washing-water were introduced;
in a third series of ten flasks a few drops of the same liquid were
placed after it had been boiled; and, finally, in the ten remaining
flasks were placed some drops of grape-juice taken from the inside of a
perfect fruit. In order to carry out this experiment, the straight tube
of each flask was drawn out into a fine and firm point in the lamp, and
then curved. This fine and closed point was filed round near the end and
inserted into the grape while resting upon some hard substance. When
the point was felt to touch the support of the grape it was by a slight
pressure broken off at the point file mark. Then, if care had been taken
to create a slight vacuum in the flask, a drop of the juice of the grape
got into it, the filed point was withdrawn, and the aperture immediately
closed in the alcohol lamp. This decreased pressure of the atmosphere in
the flask was obtained by the following means: After warming the sides
Public-domain text, read in full here on John Shaqi.
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