composed of phlogiston combined with an acid, and if metal oxides (metallic
calces) could be deprived of all their phlogiston, they would probably give rise to
acids [3]. Bergman would elaborate on these ideas after Scheele’s isolation of
molybdic and tungstic acid [4]. Scheele seems to have regarded water as an element, while Bergman spoke of “the solid part of water” as a possible constituent in
siliceous earth [5].
In his paper on pyrolusite (Sect. 15.1), Scheele noted that he obtained calcium
sulphate by dissolving pyrolusite (MnO 2 ) in sulphuric acid in the presence of sugar.
Surprisingly, Scheele did not propose an explanation but merely wrote that this
could indicate a transmutation of—in modern terms—manganese to calcium. It is
surprising that Scheele left such an important issue unresolved, but it may be that
Scheele simply wanted to finish his work, which had already been extended by
years on the request of Bergman. As Scheele was always very honest in his
description of experiments, he could still not leave the observation out. It was not
until after Scheele’s death that his friend, Gadolin, found that the calcium compounds (lime) were contaminants in the sugar [6].
22.2 Bergman’s Views on Elements
Bergman’s discussion on the nature of the elements in his preface to Scheele’s book
on air and fire, Chemische Abhandlung von der Luft und dem Feuer, in 1777 has
been studied previously; [7] there are, however, two better sources of information:
his Lecture on the Latest Progress in Chemistry from 1777 and his Instructions to
Lectures on Chemistry’s Nature and Benefits, and Natural Bodies General Differences from 1779. The later was printed as an appendix to the second edition of
The Chemical Lectures of H.T. Scheffer, but was also printed as a separate booklet
(Sect. 11.2).
In the 1779 text, Bergman defined elements as “particles, which separates by
splitting of bodies” [8]. Bergman distinguished between mechanical elements and
chemical elements. The mechanical elements were simply small homogeneous
particles obtained by mechanical division such as grinding. These could perhaps be
compared to our molecules. The chemical elements were those “of different nature,
which together constitute a body”. For example, the chemical elements of calcium
carbonate (chalk) were calcium oxide (calcareous earth), carbon dioxide (aerial
acid) and water. The chemical elements formed different orders: the proximate
elements were those which were obtained by the first decomposition, e.g. mercury
and sulphur in mercury sulphide (cinnabar). If these could be further decomposed,
remote elements were obtained. Since the proximate elements of mercury were
mercury oxide (mercury calx) and phlogiston and the proximate elements of sulphur were sulphuric acid (vitriolic acid) and phlogiston, the remote elements of
cinnabar were mercury calx, vitriolic acid and phlogiston. Elements that could not
be further decomposed were referred to as “primary elements” by Bergman, but
unfortunately, he did not explicitly state at this point whether he regarded mercury
302
22 Bergman’s and Scheele’s Theories of Elements and Atoms
calces) could be deprived of all their phlogiston, they would probably give rise to
acids [3]. Bergman would elaborate on these ideas after Scheele’s isolation of
molybdic and tungstic acid [4]. Scheele seems to have regarded water as an element, while Bergman spoke of “the solid part of water” as a possible constituent in
siliceous earth [5].
In his paper on pyrolusite (Sect. 15.1), Scheele noted that he obtained calcium
sulphate by dissolving pyrolusite (MnO 2 ) in sulphuric acid in the presence of sugar.
Surprisingly, Scheele did not propose an explanation but merely wrote that this
could indicate a transmutation of—in modern terms—manganese to calcium. It is
surprising that Scheele left such an important issue unresolved, but it may be that
Scheele simply wanted to finish his work, which had already been extended by
years on the request of Bergman. As Scheele was always very honest in his
description of experiments, he could still not leave the observation out. It was not
until after Scheele’s death that his friend, Gadolin, found that the calcium compounds (lime) were contaminants in the sugar [6].
22.2 Bergman’s Views on Elements
Bergman’s discussion on the nature of the elements in his preface to Scheele’s book
on air and fire, Chemische Abhandlung von der Luft und dem Feuer, in 1777 has
been studied previously; [7] there are, however, two better sources of information:
his Lecture on the Latest Progress in Chemistry from 1777 and his Instructions to
Lectures on Chemistry’s Nature and Benefits, and Natural Bodies General Differences from 1779. The later was printed as an appendix to the second edition of
The Chemical Lectures of H.T. Scheffer, but was also printed as a separate booklet
(Sect. 11.2).
In the 1779 text, Bergman defined elements as “particles, which separates by
splitting of bodies” [8]. Bergman distinguished between mechanical elements and
chemical elements. The mechanical elements were simply small homogeneous
particles obtained by mechanical division such as grinding. These could perhaps be
compared to our molecules. The chemical elements were those “of different nature,
which together constitute a body”. For example, the chemical elements of calcium
carbonate (chalk) were calcium oxide (calcareous earth), carbon dioxide (aerial
acid) and water. The chemical elements formed different orders: the proximate
elements were those which were obtained by the first decomposition, e.g. mercury
and sulphur in mercury sulphide (cinnabar). If these could be further decomposed,
remote elements were obtained. Since the proximate elements of mercury were
mercury oxide (mercury calx) and phlogiston and the proximate elements of sulphur were sulphuric acid (vitriolic acid) and phlogiston, the remote elements of
cinnabar were mercury calx, vitriolic acid and phlogiston. Elements that could not
be further decomposed were referred to as “primary elements” by Bergman, but
unfortunately, he did not explicitly state at this point whether he regarded mercury
302
22 Bergman’s and Scheele’s Theories of Elements and Atoms