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a permanent stutter. Soon, he began to study higher
math, natural philosophy, logic, and metaphysics. He
then returned to theological studies as a Rational Dis-
senter, one who believed in rational analysis of the nat-
ural world and the Bible. In 1758, Priestley moved to
Nantwich, Chesire, and started a theological school in
which he taught natural philosophy. After writing
The
Rudiments of English Grammar
,hewas offered a teach-
ing position at Warrington Academy in 1761. While
there, he wrote several topics on history. Of note was
The History and Present State of Electricity
, published
in 1767. This topic was inspired by a meeting between
him and Benjamin Franklin, who had recently invented
the lightning rod. Franklin suggested that Priestley per-
form several experiments, which Priestley did along
with designing experiments of his own. In one of these,
Priestley found that
graphite conducted electricity
,
overturning a theory that only water and metals could
conduct electricity. He further proposed that electri-
cal forces followed an
inverse square law
,although
Coulomb later proved this in the 1780s.
In 1767, Priestley moved to Leeds and lived in a home
next to a brewery. Curious as to the bubbly gas emanat-
ing from the brew, he found a method to produce the
gasathome. Upon experimenting, Priestley learned that
it extinguished lighted wood chips. When he dissolved
the gas in water, he noted it had a tangy taste and caused
the water to bubble. The gas was Van Helmont's and
Black's carbon dioxide, and Priestley had inadvertently
invented a drinkable form of
carbonated soda water
.
In 1772, he published a pamphlet called
Directions for
Impregnating Water with Fixed Air
,buthe did not earn
any royalties in his lifetime for this invention. Instead,
Johann Jacob Schweppe
(1740-1821) capitalized on
this invention to build a soda water empire that started
in Geneva in 1783 and move to London in 1792.
On April 15, 1770, Priestley discovered that Indian
gum could be used to rub out lead pencil marks. This
fortuitous finding was the
discovery of the eraser
,or
“rubber.” In 1772, he performed a completely different
experiment in which he placed a small green plant in
a container in which he also lit a candle. Several days
after the candle had burned out, he found that he could
light the candle again because the plant had produced
oxygen (which he had not yet discovered). Hence, he
had discovered
photosynthesis
.
In 1773, Priestley moved to Calne and began to
focus more on laboratory experimentation of gases.
In his most important experiment, he burned the ele-
ment mercury (Hg) in air to form bright red mercuric
oxide [HgO(s)], a powder. He then heated the mercuric
oxide in a container from which all air had been
Figure 1.16.
Daniel Rutherford (1749-1819). Edgar
Fahs Smith Collection, University of Pennsylvania
Library.
Chaptal
(1756-1832), a French industrial chemist,
because nitrogen was found to be a constituent of the
crystal nitre [KNO
3
(s)].
1.2.2.9. Molecular Oxygen (Gas) -
Dephlogisticated Air
Two chemists discovered
molecular oxygen
gas
[O
2
(g)] independently:
Joseph Priestley
(1733-1804;
Figure 1.17) on August 1, 1774, and
Karl Wilhelm
Scheele
(1742-1786; Figure 1.18) from Sweden,
sometime between 1772 and 1775. Although both
chemists discovered oxygen near the same time, Priest-
ley announced his discovery in 1774, and Scheele pub-
lished his discovery in 1777.
Priestley was born in 1733 in Birstall, England, the
eldest of six children in a dissenting family (one that did
not conform to the Church of England). At age nine, he
wassent to live with his aunt and uncle, who provided
him with an education in preparation for the ministry.
In 1749, he became seriously ill and, thereafter, had
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