the earth formed on refluxing water in a glass apparatus was actually silicon species
extracted from the glass. Scheele’s experiments, which were known by Gahn in
Spring 1770 (Sect. 13.2) are not mentioned, and seem to have been unknown to
Bergman. A second chapter discusses the analysis of water samples (Chapter 17).
The fourth part discusses combustible materials: sulphur, alcohol, ether, oils and
fats. Phosphorus is discussed under the section of sulphur, as the two substances are
similar in the sense that they both were thought to consist of an acid united with
phlogiston. The discovery of phosphorus in bones and horns was attributed to
Scheele without mentioning the contribution of Gahn (Sect. 13.2); this was not
corrected in the second edition. Oils were divided into two groups by Bergman.
Essential oils were soluble in alcohol and volatile at 100 °C, unlike the fatty oils.
The preparation of soap is also discussed.
The fifth part, on metals, is divided into three chapters: noble metals, full base
metals and half base metals. The noble metals had the property to resist air, water
and fire without any sign of oxidation (calcination). There were three of these
metals: gold, platinum and silver. The criterion for dividing metals into full and half
metals was based on malleability: the full metals could be shaped with a hammer
while the half metals were brittle. The full metals were mercury (frozen mercury
can indeed be shaped with a hammer), lead, copper, iron and tin. The half metals
were bismuth, nickel, arsenic, cobalt, zinc and antimony. This division may seem
strange to a modern chemist, but some of these metals were difficult to prepare in a
pure state. For example, small amounts of impurities (especially arsenic) in zinc
render the metal brittle and carbon-free nickel could not be obtained until the end of
the nineteenth century. Arsenic and antimony are still usually referred to as
semi-metals and are brittle in the pure state. The section on metals is largely
devoted to the art of purifying the metals and testing their purity. This reflects
Scheffer’s background, but also suited Bergman’s mining students. The first printed
account of the isolation of metallic manganese by Gahn (Sect. 15.3), is also found
here [17] as well as a discussion of Scheele’s discovery that arsenic(III) oxide
(white arsenic) can be oxidised to arsenic acid (Sect. 14.2), or as Bergman put it
“Arsenic [As 2 O 3 ] is nothing but a special acid, united with enough phlogiston to
keep it in a dry state” [18].
The last part of the book concerns dyeing of textiles, a special interest of
Scheffer. It is quite unlikely that Bergman would have given this topic a special
section if he would have written the book by himself. A few years later, Bergman
wrote an essay on indigo, [19] which may have been inspired by his editing of
Scheffer’s lectures.
Of some interest is also the topics not discussed in the book. Contrary to what
one could have expected, there is no section or chapter devoted to air or combustion. Oxygen (fire air, pure air) is only introduced briefly by Hjelm in the 1796
edition, but without any discussion of its properties.
11.1 Bergman’s Edition of the Chemical Lectures of H.T. Scheffer
165
extracted from the glass. Scheele’s experiments, which were known by Gahn in
Spring 1770 (Sect. 13.2) are not mentioned, and seem to have been unknown to
Bergman. A second chapter discusses the analysis of water samples (Chapter 17).
The fourth part discusses combustible materials: sulphur, alcohol, ether, oils and
fats. Phosphorus is discussed under the section of sulphur, as the two substances are
similar in the sense that they both were thought to consist of an acid united with
phlogiston. The discovery of phosphorus in bones and horns was attributed to
Scheele without mentioning the contribution of Gahn (Sect. 13.2); this was not
corrected in the second edition. Oils were divided into two groups by Bergman.
Essential oils were soluble in alcohol and volatile at 100 °C, unlike the fatty oils.
The preparation of soap is also discussed.
The fifth part, on metals, is divided into three chapters: noble metals, full base
metals and half base metals. The noble metals had the property to resist air, water
and fire without any sign of oxidation (calcination). There were three of these
metals: gold, platinum and silver. The criterion for dividing metals into full and half
metals was based on malleability: the full metals could be shaped with a hammer
while the half metals were brittle. The full metals were mercury (frozen mercury
can indeed be shaped with a hammer), lead, copper, iron and tin. The half metals
were bismuth, nickel, arsenic, cobalt, zinc and antimony. This division may seem
strange to a modern chemist, but some of these metals were difficult to prepare in a
pure state. For example, small amounts of impurities (especially arsenic) in zinc
render the metal brittle and carbon-free nickel could not be obtained until the end of
the nineteenth century. Arsenic and antimony are still usually referred to as
semi-metals and are brittle in the pure state. The section on metals is largely
devoted to the art of purifying the metals and testing their purity. This reflects
Scheffer’s background, but also suited Bergman’s mining students. The first printed
account of the isolation of metallic manganese by Gahn (Sect. 15.3), is also found
here [17] as well as a discussion of Scheele’s discovery that arsenic(III) oxide
(white arsenic) can be oxidised to arsenic acid (Sect. 14.2), or as Bergman put it
“Arsenic [As 2 O 3 ] is nothing but a special acid, united with enough phlogiston to
keep it in a dry state” [18].
The last part of the book concerns dyeing of textiles, a special interest of
Scheffer. It is quite unlikely that Bergman would have given this topic a special
section if he would have written the book by himself. A few years later, Bergman
wrote an essay on indigo, [19] which may have been inspired by his editing of
Scheffer’s lectures.
Of some interest is also the topics not discussed in the book. Contrary to what
one could have expected, there is no section or chapter devoted to air or combustion. Oxygen (fire air, pure air) is only introduced briefly by Hjelm in the 1796
edition, but without any discussion of its properties.
11.1 Bergman’s Edition of the Chemical Lectures of H.T. Scheffer
165