also be bodies traversing Universe or possibly bodies orbiting the sun like comets.
A less likely explanation was that they were ejected from volcanoes. Bergman was
not aware of any chemical investigations of meteorites.
The fifth part deals with changes occurring on Earth. First, Bergman discussed
day and night, different climates and seasons. It is clear that there was a reservoir of
heat at the core of the Earth, but Bergman could not imagine any other source for
that heat than the Sun: Bergman believed that Earth had accumulated heat from
sunshine since the creation [44]. Of course, Bergman and his contemporaries could
not have anticipated the true source of this energy over a century before the discovery of radioactivity. In the next chapter, Bergman discussed changes of geological origin. For instance, fossilised trees had been found deep down in the
ground, a clear proof that Earth is changing. Subterranean fire [45] could, according
to Bergman, cause both land rise and land sinking. Volcanoes, Bergman wrote, are
chimneys where vapours, smoke and ashes can escape from these subterranean
fires; without means of releasing this pressure, earthquakes arise. After a long
description of volcanoes and volcanic materials, Bergman turned to the explanation
of these supposed subterranean fires [46]. He found a constant fire within Earth
unlikely and was more inclined towards local chemical reactions. One possibility,
according to Bergman, was the reaction between iron and sulphur. When a moist
mixture of powdered iron and sulphur is exposed to air, it turns red-hot. This
reaction was also investigated by Scheele [47]. As the Earth was unlikely to contain
large amounts of elemental sulphur and iron, Bergman instead suggested that
pyrites (iron sulphide) may ignite layers of coal or alum shale. In 1780, Bergman
returned to volcanoes in a long paper reporting chemical analysis of volcanic
materials [48].
Chapter 3 deals with an important issue for the geologists of Bergman’s time:
water decrease. Sedimentary rocks and giant’s kettles, for instance, indicated that
dry land had once been covered with water. So, where is this water today? First of
all, rather than a decrease in water, it could be a land rise, although Bergman found
water decrease quite likely [49]. A common explanation was the conversion of
water to earth, but Bergman was not convinced and referred to Lavoisier’s famous
experiment where it was found, by weighing, that the earth deposited on refluxing
water in a glass vessel originated from the glass. He was apparently unaware of
Scheele’s similar results that are found in Gahn’s notes from 1770 (Sect. 13.2).
Chapter 4, 120 pages long in the second edition, deals with the creation of the
Earth. Bergman’s opinion was that God had established the natural laws that regulated the changes on Earth. Bergman rejected the idea that the interior of Earth was
filled with fire, instead he agreed with those suggesting a homogeneous magnetic
core [50]. The core was surrounded with bed rock that Bergman classified as
ancient (uråldig), as it was probably as old as Earth itself.
3 This type of rock formed
many of the mountains and contained no petrifications (fossils). The second type of
rocks was far less voluminous, and Bergman called them layered (flolägrige) rocks.
3
This is not true. There are no remaining traces of Earth’s original crust.
90
7 Bergman’s Geological Work
A less likely explanation was that they were ejected from volcanoes. Bergman was
not aware of any chemical investigations of meteorites.
The fifth part deals with changes occurring on Earth. First, Bergman discussed
day and night, different climates and seasons. It is clear that there was a reservoir of
heat at the core of the Earth, but Bergman could not imagine any other source for
that heat than the Sun: Bergman believed that Earth had accumulated heat from
sunshine since the creation [44]. Of course, Bergman and his contemporaries could
not have anticipated the true source of this energy over a century before the discovery of radioactivity. In the next chapter, Bergman discussed changes of geological origin. For instance, fossilised trees had been found deep down in the
ground, a clear proof that Earth is changing. Subterranean fire [45] could, according
to Bergman, cause both land rise and land sinking. Volcanoes, Bergman wrote, are
chimneys where vapours, smoke and ashes can escape from these subterranean
fires; without means of releasing this pressure, earthquakes arise. After a long
description of volcanoes and volcanic materials, Bergman turned to the explanation
of these supposed subterranean fires [46]. He found a constant fire within Earth
unlikely and was more inclined towards local chemical reactions. One possibility,
according to Bergman, was the reaction between iron and sulphur. When a moist
mixture of powdered iron and sulphur is exposed to air, it turns red-hot. This
reaction was also investigated by Scheele [47]. As the Earth was unlikely to contain
large amounts of elemental sulphur and iron, Bergman instead suggested that
pyrites (iron sulphide) may ignite layers of coal or alum shale. In 1780, Bergman
returned to volcanoes in a long paper reporting chemical analysis of volcanic
materials [48].
Chapter 3 deals with an important issue for the geologists of Bergman’s time:
water decrease. Sedimentary rocks and giant’s kettles, for instance, indicated that
dry land had once been covered with water. So, where is this water today? First of
all, rather than a decrease in water, it could be a land rise, although Bergman found
water decrease quite likely [49]. A common explanation was the conversion of
water to earth, but Bergman was not convinced and referred to Lavoisier’s famous
experiment where it was found, by weighing, that the earth deposited on refluxing
water in a glass vessel originated from the glass. He was apparently unaware of
Scheele’s similar results that are found in Gahn’s notes from 1770 (Sect. 13.2).
Chapter 4, 120 pages long in the second edition, deals with the creation of the
Earth. Bergman’s opinion was that God had established the natural laws that regulated the changes on Earth. Bergman rejected the idea that the interior of Earth was
filled with fire, instead he agreed with those suggesting a homogeneous magnetic
core [50]. The core was surrounded with bed rock that Bergman classified as
ancient (uråldig), as it was probably as old as Earth itself.
3 This type of rock formed
many of the mountains and contained no petrifications (fossils). The second type of
rocks was far less voluminous, and Bergman called them layered (flolägrige) rocks.
3
This is not true. There are no remaining traces of Earth’s original crust.
90
7 Bergman’s Geological Work