Today, let's try to find out who discovered oxygen.
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.
In his 1962 bombshell-book
about scientific change, The Structure of
Scientific Revolutions, Thomas Kuhn gave us a
whole new way to think about priority. Kuhn showed
that revolutionary scientific change was never the
work of a single genius. Rather, it occurs when new
communities form around wholly new scientific
outlooks.
Kuhn does this best when he talks about the
"discovery" of oxygen. You and I know perfectly
well that the oxygen in air reacts with other
materials when they burn. But eighteenth-century
chemists thought burning materials were simply
releasing an invisible fluid called
phlogiston, which caused heating. No one
supposed burning had anything to do with the air
itself. They had no idea that oxygen, which makes
up one fifth of air, was the active agent.
Three people finally pinned oxygen down as a
separate element in the 1770s: an English cleric
named Priestley, the
French chemist Lavoisier,
and a Swedish pharmacist named Scheele. When
Priestley isolated oxygen in 1774, he thought he
had laughing gas. A year later he decided he'd
actually taken the phlogiston out of air. At the
same time, Lavoisier (who knew about Priestley's
work) also isolated oxygen. He thought it was very
pure air.
Two years later, Lavoisier realized he'd actually
separated a component of air; but he thought it was
something that came into existence only when air
was heated. Meanwhile, the Swede Scheele had been
working quietly. He published a book titled Air
and Fire just after Lavoisier uttered his final
word on the matter. Based on work he'd done before
either Priestley or Lavoisier, Scheele realized
that oxygen was a separate part of air.
Kuhn uses this muddle to undercut all our talk
about who got there first -- to show how squabbles
over who gets credit cloud the real story. Should
we credit Priestley, who isolated oxygen -- then
went to his death thinking it was something else?
Lavoisier, who saw it was part of air but didn't
know it was a new element? And what can we say
about Scheele, who was slow to publish his results?
The fact is that oxygen couldn't possibly have been
understood in terms that you and I find acceptable.
Scientists first had to change their whole view of
matter. Priestley started a scientific revolution
that couldn't be finished until John Dalton built oxygen into the
atomic theory of matter thirty years later.
The idea that burning meant new combinations of
atoms was too great a leap for any one
person to make. Pieces of the puzzle added up until
an unexpected new picture suddenly burst free.
Oxygen wasn't discovered at all. Oxygen as we know
it couldn't've been perceived, much less
discovered, until a whole new science was forged to
accommodate it. Priestley, Lavoisier, Scheele, and
Dalton each added new insights, but the game
couldn't be concluded until it'd added up to a
major scientific revolution.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
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