that metals may appear in higher oxidation states than in the commonly encountered
hydrated metal ions, and that such species frequently are acidic.
It is unlikely that Bergman would have believed in chemical transmutation, but
on the other hand, when discussing the history of chemistry, he wrote that “…the
alchemists work on a solution of a problem [i.e. transmutation of base metals to
gold], that cannot be proved to be impossible […]” [13].
22.3 Bergman’s and Scheele’s Views on Atoms
That matter was composed of particles seems to have been absolutely natural to
both Scheele and Bergman, and they never discussed other possibilities. Bergman
even used the word “atom” when describing water, and assumed that the particles
were solid:
The particles of water are, however, probably solid, since one can generally hardly imagine
a fluid differently, than as a collection of such fine atoms, that they cannot be seen with the
best armed eye, and so moveable, that their equilibrium requires a horizontal surface. [14]
The liquid nature of water was caused by heat, which was so firmly intermixed
with the water particles that it could not be detected by a thermometer. The particles
of matter attracted each other, giving rise to affinities (Chap. 20): “The elements
union is caused by their mutual attractions […]. All bodies in nature attract each
other” [15]. With his background in astronomy, Bergman compared these attractions with the gravitational attractions between celestial bodies. In the gaseous state,
Bergman found that “particles are not only easily separable, but seem in some
degree to repel each other” [16]. It would take another century and the work of
Maxwell, Boltzmann and others until the properties of gases could be understood at
a molecular level. While Bergman described the water atoms as solid, he described
air particles as compressible in 1764 when discussing the decrease in air pressure
with altitude: “Now it is quite uncertain how many times an air particles volume has
decreased by compression from its natural size at the Earth surface […]” [17].
Scheele mentioned the particulate nature of matter on a few occasions, most
notably in his discussion on heat and light in his book on Air and Fire. Heat,
Scheele wrote, cannot penetrate matter but is absorbed in voids between the particles [18]. On heating a stone, it first absorbed heat into its pores, and by doing so,
it expanded. On expanding, finer pores were made accessible and could accommodate light. This explained thermal expansion and incandescence (the emission of
light by hot objects) [19].
It should be noted that neither Bergman’s nor Scheele’s views on atoms were
clear enough to enable them to use atomic theories to explain chemical phenomena.
Atoms or particles were used to describe physical properties of matter, but they
rarely discussed the relation between elements and atoms. They did not state
whether they believed that all atoms of an element were identical and different from
atoms of other elements.
304
22 Bergman’s and Scheele’s Theories of Elements and Atoms
hydrated metal ions, and that such species frequently are acidic.
It is unlikely that Bergman would have believed in chemical transmutation, but
on the other hand, when discussing the history of chemistry, he wrote that “…the
alchemists work on a solution of a problem [i.e. transmutation of base metals to
gold], that cannot be proved to be impossible […]” [13].
22.3 Bergman’s and Scheele’s Views on Atoms
That matter was composed of particles seems to have been absolutely natural to
both Scheele and Bergman, and they never discussed other possibilities. Bergman
even used the word “atom” when describing water, and assumed that the particles
were solid:
The particles of water are, however, probably solid, since one can generally hardly imagine
a fluid differently, than as a collection of such fine atoms, that they cannot be seen with the
best armed eye, and so moveable, that their equilibrium requires a horizontal surface. [14]
The liquid nature of water was caused by heat, which was so firmly intermixed
with the water particles that it could not be detected by a thermometer. The particles
of matter attracted each other, giving rise to affinities (Chap. 20): “The elements
union is caused by their mutual attractions […]. All bodies in nature attract each
other” [15]. With his background in astronomy, Bergman compared these attractions with the gravitational attractions between celestial bodies. In the gaseous state,
Bergman found that “particles are not only easily separable, but seem in some
degree to repel each other” [16]. It would take another century and the work of
Maxwell, Boltzmann and others until the properties of gases could be understood at
a molecular level. While Bergman described the water atoms as solid, he described
air particles as compressible in 1764 when discussing the decrease in air pressure
with altitude: “Now it is quite uncertain how many times an air particles volume has
decreased by compression from its natural size at the Earth surface […]” [17].
Scheele mentioned the particulate nature of matter on a few occasions, most
notably in his discussion on heat and light in his book on Air and Fire. Heat,
Scheele wrote, cannot penetrate matter but is absorbed in voids between the particles [18]. On heating a stone, it first absorbed heat into its pores, and by doing so,
it expanded. On expanding, finer pores were made accessible and could accommodate light. This explained thermal expansion and incandescence (the emission of
light by hot objects) [19].
It should be noted that neither Bergman’s nor Scheele’s views on atoms were
clear enough to enable them to use atomic theories to explain chemical phenomena.
Atoms or particles were used to describe physical properties of matter, but they
rarely discussed the relation between elements and atoms. They did not state
whether they believed that all atoms of an element were identical and different from
atoms of other elements.
304
22 Bergman’s and Scheele’s Theories of Elements and Atoms