Theoretically, the observation of oxygen could have appeared in the original
manuscript. If not, it may perhaps be that Scheele initially assumed that the formation of oxygen by heating saltpetre was well known. Of course, the evolution of
gas from hot saltpetre had been noted by British priest and amateur botanist Stephen
Hales in his Vegetable Staticks from 1727, but the nature of this gas had escaped
notice. The fact that saltpetre supported combustion had also been known for
centuries; it had been used in gunpowder since the Chinese Song dynasty. On the
contrary, it could also be that Scheele found his discovery so remarkable, that he
initially could not fit the discovery into his manuscript. This seems less likely, as
Scheele always reported all his observations in an honest manner.
(2) Scheele discovered oxygen in Stockholm. As there are no letters preserved from
his time in Stockholm, Scheele could simply have told Retzius and his friends of his
discovery and there would have been little reason to discuss it in letters after he
arrived in Uppsala. If Scheele discovered oxygen at such an early date, it is likely
that it took him several years, just as Oseen assumed, to work out a theory of heat,
combustion and phlogiston that included oxygen. The discovery is not, however,
mentioned in Gahn’s notes from spring 1770, and it still does not explain why it
was never mentioned to Bergman.
(3) Scheele discovered oxygen in Uppsala. If Scheele discovered oxygen in Uppsala, it seems that he must deliberately kept the discovery a secret. There could be
two reasons for doing so. Usually Scheele seems to have shared information freely
with friends, so it is less likely that he was afraid of anyone stealing his idea.
Perhaps the discovery confused him and he needed time to sort out his thoughts, as
Oseen suggested. If he had told Bergman at an early stage, Bergman would have
surely worked out a theory for Scheele, but one can assume that Scheele felt that
would have deprived him from some of the excitement.
21.2 Priestley’s Discovery of Oxygen
Joseph Priestley (Fig. 21.3) was born in Leeds, England, on March 24, 1733, and as
a person he was, in many respects, the complete opposite of Scheele. As a child, he
suffered from poor health and his education was not very organised: he focused on
languages and religion. He initially worked as a teacher and preacher, and his
interest in natural science did not arise until 1766; the following year he published
his book History of Electricity. In 1772, he was hired as “literary companion” by
Lord Shelburne (1737–1805), and it was at this point that Priestley became interested in chemistry and started investigating combustion phenomena. He isolated
oxygen on August 1, 1774 by heating mercury oxide with a burning glass, an
experiment carried out at Lord Shelburne’s country residence Bowood House, near
Calne, in Wiltshire. There is thus no doubt that Scheele isolated oxygen before
Priestley. In 1780, Priestley moved to Birmingham, but his liberal religious and
political views made him highly controversial and his support for the French
21.1 Scheele’s Discovery of Oxygen
281
manuscript. If not, it may perhaps be that Scheele initially assumed that the formation of oxygen by heating saltpetre was well known. Of course, the evolution of
gas from hot saltpetre had been noted by British priest and amateur botanist Stephen
Hales in his Vegetable Staticks from 1727, but the nature of this gas had escaped
notice. The fact that saltpetre supported combustion had also been known for
centuries; it had been used in gunpowder since the Chinese Song dynasty. On the
contrary, it could also be that Scheele found his discovery so remarkable, that he
initially could not fit the discovery into his manuscript. This seems less likely, as
Scheele always reported all his observations in an honest manner.
(2) Scheele discovered oxygen in Stockholm. As there are no letters preserved from
his time in Stockholm, Scheele could simply have told Retzius and his friends of his
discovery and there would have been little reason to discuss it in letters after he
arrived in Uppsala. If Scheele discovered oxygen at such an early date, it is likely
that it took him several years, just as Oseen assumed, to work out a theory of heat,
combustion and phlogiston that included oxygen. The discovery is not, however,
mentioned in Gahn’s notes from spring 1770, and it still does not explain why it
was never mentioned to Bergman.
(3) Scheele discovered oxygen in Uppsala. If Scheele discovered oxygen in Uppsala, it seems that he must deliberately kept the discovery a secret. There could be
two reasons for doing so. Usually Scheele seems to have shared information freely
with friends, so it is less likely that he was afraid of anyone stealing his idea.
Perhaps the discovery confused him and he needed time to sort out his thoughts, as
Oseen suggested. If he had told Bergman at an early stage, Bergman would have
surely worked out a theory for Scheele, but one can assume that Scheele felt that
would have deprived him from some of the excitement.
21.2 Priestley’s Discovery of Oxygen
Joseph Priestley (Fig. 21.3) was born in Leeds, England, on March 24, 1733, and as
a person he was, in many respects, the complete opposite of Scheele. As a child, he
suffered from poor health and his education was not very organised: he focused on
languages and religion. He initially worked as a teacher and preacher, and his
interest in natural science did not arise until 1766; the following year he published
his book History of Electricity. In 1772, he was hired as “literary companion” by
Lord Shelburne (1737–1805), and it was at this point that Priestley became interested in chemistry and started investigating combustion phenomena. He isolated
oxygen on August 1, 1774 by heating mercury oxide with a burning glass, an
experiment carried out at Lord Shelburne’s country residence Bowood House, near
Calne, in Wiltshire. There is thus no doubt that Scheele isolated oxygen before
Priestley. In 1780, Priestley moved to Birmingham, but his liberal religious and
political views made him highly controversial and his support for the French
21.1 Scheele’s Discovery of Oxygen
281