Today let's talk about hydrogen in 1783. The
University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
Hydrogen is a wonderful
mouthful of a word. Antoine Lavoisier named it in
1783, after he realized that it makes water when
it's burned in oxygen. Hydrogen means "maker of
water" in Greek. But the substance was known before
that. The 16th-century Swiss alchemist Paracelsus separated it, but he
seems to have confused it with other flammable
gases.
Hydrogen came to public attention 17 years before
Lavoisier named it. The English chemist Henry
Cavendish identified it. He thought it was a kind
of inflammable, or phlogisticated, air. Phlogiston
was the old alchemical principle of combustion. By
1783 Cavendish had also seen that hydrogen formed
water when it was burned; but he didn't realize
that oxygen was involved, too.
1783 was also the year the French began making
balloon ascents in Paris. The Montgolfier brothers
used hot air in the first manned balloon. Hot air
is easy enough to come by, but its density is only
a little less than the cool air around it. Whatever
people thought hydrogen was, they knew it was very
light -- about 1/15th the density of air. It had
terrific lifting power in a balloon.
The champion of hydrogen-filled balloons was
Alexandre Charles -- a French physicist. He flew an
unmanned hydrogen balloon just before the
Montgolfiers' flight, and a manned one only
3½ months after it. He invented a hydrogen
generator that worked by mixing huge quantities of
sulfuric acid with iron filings.
London sneered at the French balloons, but there
was a better intellectual climate further north. In
Birmingham, movers and shakers like Watt,
Priestley, Wedgwood, Boulton, and Erasmus Darwin
met in a scientific club called the Lunar Society.
They weren't interested in flying, but they saw
scientific possibilities in the French balloons.
In 1784 Watt and Boulton built an unmanned paper
balloon. They filled it with air and hydrogen and
launched it with a timed fuse. They wanted to find
out whether the reverberating sound of thunder was
the result of repeated claps or of echoes. The
experiment was inconclusive, but the explosion they
set off was apparently a grand and soul-satisfying
one.
The early balloonists put words like inflammable
air and phlogiston on every tongue. These huge
hydrogen-filled spheres dressed the sky in
fantastic colors and caught the public's fancy.
Balloons hurried the process of taking chemistry
out of the alchemical laboratories and tying it to
the high technology of the Industrial Revolution.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
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