experiments in order to find out whether pure water could dissolve iron, or if the
solubility of iron was caused by another substance present in water. He came across
Lane’s paper claiming that carbon dioxide (fixed air) was required for water to
dissolve iron [9]. “This”, Retzius wrote, “I commissioned Scheele to repeat. He
came to me completely happy one morning, and told me completely satisfied, that
he evidently had found that the so called Aer fixus [carbon dioxide] had all properties of a weak acid”. In Uppsala, Scheele told Gahn about his findings on carbon
dioxide, and these experiments are found in Gahn’s notes written in spring 1770: “If
Aer fixus is caught in water, it reacts with litmus as an acid, despite all efforts to
exclude any acidic vapour. After some time, this air evaporates away and the litmus
turns blue again”. Via Gahn, this knowledge may have reached Bergman, and may
have put Bergman on the right track in his search for an acid in air (Sect. 18.3). On
the other hand, Bergman was apparently unaware of Scheele’s investigation of the
transformation of water to earth in the same manuscript, so Bergman’s work may be
independent of Scheele’s.
18.2 Scheele’s Later Views on Carbon Dioxide
As Scheele learned about Black’s hypothesis, he abandoned his support for Meyer,
and joined the international discussion on the nature of carbon dioxide. In 1778,
Jacob Andreas Weber published a book concluding that the theories of both Black
and Meyer were wrong [10]. Weber’s theory was that heat arises from electrical
matter emanating from the sun, and it was this electric matter, in the form of
phlogiston, which was removed from mild alkalis by quicklime [11]. Scheele was
not impressed by this theory, and criticised it in a letter to J. C. F. Meyer
4 , a letter
which Crell published [12] with Scheele’s permission. Weber’s response in Crell’s
Neuesten Entdeckungen in der Chemie [13] caused Scheele to write a second letter
where he (on good grounds) seriously questioned Weber’s experimental skills:
“I cannot understand, how he has performed his experiments” [14].
Kirwan had in 1782 concluded that carbon dioxide was composed of phlogiston
and oxygen,
5 a subject that he discussed in letters with Bergman [15]. By 1783, he
had convinced Bergman, but Scheele never accepted this theory. In a letter to Crell
published in 1784, Kirwan wrote that Priestley had established the composition of
carbon dioxide (fixed air) without all doubt: he had obtained carbon dioxide by
burning iron in oxygen (dephlogisticated air) and by heating mercury(II) oxide (red
precipitated mercury) with iron flings [16]. Later the same year, Crell published a
letter from Scheele, including a comment on carbon dioxide (aerial acid), where
Scheele maintained that it had not been proven that carbon dioxide was composed
of oxygen (pure air) and phlogiston [17]. Scheele mentioned neither Priestley nor
Kirwan. Another letter from Scheele to Crell followed, where Scheele correctly
4
Not to be confused with J. F. Meyer, who launched Acidum pingue hypothesis.
5
It would be correct for someone identifying phlogiston with carbon.
18.1 Scheele and the Acidic Properties of Carbon Dioxide
247
solubility of iron was caused by another substance present in water. He came across
Lane’s paper claiming that carbon dioxide (fixed air) was required for water to
dissolve iron [9]. “This”, Retzius wrote, “I commissioned Scheele to repeat. He
came to me completely happy one morning, and told me completely satisfied, that
he evidently had found that the so called Aer fixus [carbon dioxide] had all properties of a weak acid”. In Uppsala, Scheele told Gahn about his findings on carbon
dioxide, and these experiments are found in Gahn’s notes written in spring 1770: “If
Aer fixus is caught in water, it reacts with litmus as an acid, despite all efforts to
exclude any acidic vapour. After some time, this air evaporates away and the litmus
turns blue again”. Via Gahn, this knowledge may have reached Bergman, and may
have put Bergman on the right track in his search for an acid in air (Sect. 18.3). On
the other hand, Bergman was apparently unaware of Scheele’s investigation of the
transformation of water to earth in the same manuscript, so Bergman’s work may be
independent of Scheele’s.
18.2 Scheele’s Later Views on Carbon Dioxide
As Scheele learned about Black’s hypothesis, he abandoned his support for Meyer,
and joined the international discussion on the nature of carbon dioxide. In 1778,
Jacob Andreas Weber published a book concluding that the theories of both Black
and Meyer were wrong [10]. Weber’s theory was that heat arises from electrical
matter emanating from the sun, and it was this electric matter, in the form of
phlogiston, which was removed from mild alkalis by quicklime [11]. Scheele was
not impressed by this theory, and criticised it in a letter to J. C. F. Meyer
4 , a letter
which Crell published [12] with Scheele’s permission. Weber’s response in Crell’s
Neuesten Entdeckungen in der Chemie [13] caused Scheele to write a second letter
where he (on good grounds) seriously questioned Weber’s experimental skills:
“I cannot understand, how he has performed his experiments” [14].
Kirwan had in 1782 concluded that carbon dioxide was composed of phlogiston
and oxygen,
5 a subject that he discussed in letters with Bergman [15]. By 1783, he
had convinced Bergman, but Scheele never accepted this theory. In a letter to Crell
published in 1784, Kirwan wrote that Priestley had established the composition of
carbon dioxide (fixed air) without all doubt: he had obtained carbon dioxide by
burning iron in oxygen (dephlogisticated air) and by heating mercury(II) oxide (red
precipitated mercury) with iron flings [16]. Later the same year, Crell published a
letter from Scheele, including a comment on carbon dioxide (aerial acid), where
Scheele maintained that it had not been proven that carbon dioxide was composed
of oxygen (pure air) and phlogiston [17]. Scheele mentioned neither Priestley nor
Kirwan. Another letter from Scheele to Crell followed, where Scheele correctly
4
Not to be confused with J. F. Meyer, who launched Acidum pingue hypothesis.
5
It would be correct for someone identifying phlogiston with carbon.
18.1 Scheele and the Acidic Properties of Carbon Dioxide
247