The third part concerns water. The first chapter deals with springs and the origin
of the water from springs. Rainwater was a frequent source, but a spring may also
be connected to an underground cavity, a lake or the sea. Of special interest to
Bergman were hot springs, especially the geysers on Iceland, which Bergman
claimed were powered by underground fire [36]. Not surprisingly, the sections
dealing with the chemical compositions of mineral waters were expanded in the
second edition, written after he became a professor of chemistry (Sect. 9.3). The
remaining chapters of part 3 deal with rivers, swamps, lakes and seas, respectively.
In the chapter of lakes, Bergman claimed that some lakes were stirred up by activity
on the bottom as waves form in calm weather without the aid of wind. Bergman
attributed this to chemical reactions in underground caves: “Nature’s workshop is
constantly in action, new bodies are formed, old are destroyed, and during all this
an air-like spirit is released from the compound where it used to be a part” [37].
Regarding the sea, Bergman remarked that the sea floor is not different from dry
land, it just happens to be covered with water. Bergman wrote that the salt in the sea
serves the purpose of facilitating fast degradation of dead plants and animals and
that the Lord had added just the perfect amount of salt to assure that dead bodies
rapidly dissolve [38].
The topic for the fourth part is the atmosphere. The most striking thing is that
there is no mention of Scheele’s discovery of oxygen (Chapter 21) in the second
edition, and it is clear that this important information was still unknown to Bergman
in 1774. Instead, Bergman appears to have regarded air as a single substance: “The
main substance [in the atmosphere] is air” [39]. This air was, according to Bergman,
composed of particles. The atmosphere also contained many foreign substances
such as water vapour and combustible dust, which gave rise to “air fires”, e.g.
auroras. Bergman mentioned carbon dioxide (aerial acid) and the electrical substance that gives rise to lightings.
Bergman discussed the expansion of air by heat, and the much lower density of
steam compared to liquid water. He speculated that steam is a compound between
fire and water, but he did not believe that steam was air, since air cannot be
condensed by compression. Through his work on the twilights, [40] he knew that
the atmosphere only refracts light to a certain altitude and that the atmosphere does
not extend infinitely into space.
Chapter 4 deals with “air fires”, a category including such different phenomena
as lightning, auroras and meteors. One explanation was volatile flammable substances that evaporated from plants and busted into flame at high altitude. The true
nature of meteors was not recognised until 1794 [41] and received more attention
from the works of Davy [42]. In many cases, however, electricity was involved, but
Bergman could not explain how electrical charges arise in the atmosphere. Rubbing
of air particles against each other would, according to Bergman, give equal amounts
of positive and negative electricity that would soon cancel each other out. Since
lightings are rarely seen in the winter, temperature differences might play a crucial
role according to Bergman. Meteorites were difficult to explain, [43] and Bergman
discussed the different theories. Meteors may be aggregates of particles formed
within the atmosphere, although Bergman found this hard to believe. Meteors may
7.2 Physical Description of the Earth
89
of the water from springs. Rainwater was a frequent source, but a spring may also
be connected to an underground cavity, a lake or the sea. Of special interest to
Bergman were hot springs, especially the geysers on Iceland, which Bergman
claimed were powered by underground fire [36]. Not surprisingly, the sections
dealing with the chemical compositions of mineral waters were expanded in the
second edition, written after he became a professor of chemistry (Sect. 9.3). The
remaining chapters of part 3 deal with rivers, swamps, lakes and seas, respectively.
In the chapter of lakes, Bergman claimed that some lakes were stirred up by activity
on the bottom as waves form in calm weather without the aid of wind. Bergman
attributed this to chemical reactions in underground caves: “Nature’s workshop is
constantly in action, new bodies are formed, old are destroyed, and during all this
an air-like spirit is released from the compound where it used to be a part” [37].
Regarding the sea, Bergman remarked that the sea floor is not different from dry
land, it just happens to be covered with water. Bergman wrote that the salt in the sea
serves the purpose of facilitating fast degradation of dead plants and animals and
that the Lord had added just the perfect amount of salt to assure that dead bodies
rapidly dissolve [38].
The topic for the fourth part is the atmosphere. The most striking thing is that
there is no mention of Scheele’s discovery of oxygen (Chapter 21) in the second
edition, and it is clear that this important information was still unknown to Bergman
in 1774. Instead, Bergman appears to have regarded air as a single substance: “The
main substance [in the atmosphere] is air” [39]. This air was, according to Bergman,
composed of particles. The atmosphere also contained many foreign substances
such as water vapour and combustible dust, which gave rise to “air fires”, e.g.
auroras. Bergman mentioned carbon dioxide (aerial acid) and the electrical substance that gives rise to lightings.
Bergman discussed the expansion of air by heat, and the much lower density of
steam compared to liquid water. He speculated that steam is a compound between
fire and water, but he did not believe that steam was air, since air cannot be
condensed by compression. Through his work on the twilights, [40] he knew that
the atmosphere only refracts light to a certain altitude and that the atmosphere does
not extend infinitely into space.
Chapter 4 deals with “air fires”, a category including such different phenomena
as lightning, auroras and meteors. One explanation was volatile flammable substances that evaporated from plants and busted into flame at high altitude. The true
nature of meteors was not recognised until 1794 [41] and received more attention
from the works of Davy [42]. In many cases, however, electricity was involved, but
Bergman could not explain how electrical charges arise in the atmosphere. Rubbing
of air particles against each other would, according to Bergman, give equal amounts
of positive and negative electricity that would soon cancel each other out. Since
lightings are rarely seen in the winter, temperature differences might play a crucial
role according to Bergman. Meteorites were difficult to explain, [43] and Bergman
discussed the different theories. Meteors may be aggregates of particles formed
within the atmosphere, although Bergman found this hard to believe. Meteors may
7.2 Physical Description of the Earth
89