Louis Pasteur by Nicola Kingsley - National STEM Centre

Mer de Glace on
Mont Blanc
where Pasteur
carried out some
of his
experiments
18
over 200 miles and heading up into the Jura mountains
with his assistants and a large supply of sealed flasks
containing a sterile mixture of sugar, water and yeast
extract-good food for microbes. At different heights up
the mountains he carefully broke the necks of the flasks to
admit fresh air, and then resealed them using a flame. The
higher they went up the mountains, the fewer of the flasks
exposed to air in this way grew any microbes. Because the
air was so clean, especially right at the top among the
glaciers, some developed no microbes at all. Once again
Pasteur showed that fresh air alone was unable to give rise
to microbes.
Pouchet, too, was a fighter. He set off up another range of
mountains, the Alps, to try the experiment, and he came
back saying he had got different results. Every single flask
he had opened developed microbes.
Pasteur demanded that the Academy of Sciences repeat his
experiments. He was completely sure his own results were
correct, and he wanted Pouchet to be shown, in public, to
be wrong. The experiments were done again, and the
Academy announced their decision: Pasteur was right.