surprising that d’Elhuyar went on to study tungstic acid and isolate metallic
tungsten once back in Spain.
The section on alkali is very short, and includes the odd statement that alum does
not crystallise without addition of sodium carbonate (mineral alkali). This is of
course wrong and on the contrary to Bergman’s findings (Sect. 15.2).
In the section of salts, Bergman’s classification system is discussed followed by
a discussion of “neutral salts” and “metallic salts”. The green colour of hydrated
iron(II) salts was attributed to phlogiston, since it was not observed after removal of
phlogiston (oxidation to Fe
3+ ).
In the section of earths, Bergman speculated that the “heavy earth” (barium
oxide) could possibly be reduced to a metal. Scheele was of the same opinion
(Sect. 15.2), but the isolation of barium was not achieved until the nineteenth
century.
After the earths, different combustible materials were discussed: sulphur,
phosphorus, “pyrophore” (Sect. 28.5), oils, camphor, ether and charcoal. On discussing phosphorus, Bergman also discussed other phosphorescent materials such
as barium sulphide and the theory of Beccaria
4 that phosphorescence is due to
absorption of light. The discussion of ether is rather confusing and it appears that
d’Elhuyar (or the person who copied the notes) did not understand the difference
between diethyl ether and ethyl acetate. Bergman mentioned the discovery (by
Scheele, Sect. 24.8) that mineral acid is needed for the formation of ethyl acetate,
but the text suggests that ethyl acetate and diethyl ether were one and the same
compound. Bergman would not have made such an error. On discussing charcoal,
Bergman noted its similarity to coal and soot, and finally gave the recipe for an ink
suitable for marking sheep. Finally, fulminant powder (a mixture of sulphur, alkali
and potassium nitrate) and gun powder were discussed.
Bergman then turned to the metals and their characteristic properties. He discussed his investigation of the phlogiston content of metals (Sect. 22.5) and
attempted to prove that the hydrogen gas evolved by dissolving metals in acids
originates from the metal rather than from the acid.
Bergman then discussed water and heat, and stressed that water is composed of
extremely small solid particles (Sect. 22.3). Bergman gave a long discussion on
heat, and seems to adhere to Scheele’s theory that it was composed of oxygen (vital
air) and phlogiston and that light was composed of heat and phlogiston. Bergman
explained the difference between temperature and specific heat, but the latter use of
the term “specific heat” is rather confusing, and with Bergman’s background as a
physicist, it seems more likely that it is d’Elhuyar who was confused.
The last section discussed air and oxygen. He discussed the importance of
oxygen for living organisms and the effect of oxygen on blood. He also discussed
the evolution of oxygen by green plants, and assured that even toxic and
bad-smelling plants were as effective in this regard.
4
Giacomo Battista Beccaria (1716–1781). Italian physicist.
11.3 Bergman’s Lectures
171
tungsten once back in Spain.
The section on alkali is very short, and includes the odd statement that alum does
not crystallise without addition of sodium carbonate (mineral alkali). This is of
course wrong and on the contrary to Bergman’s findings (Sect. 15.2).
In the section of salts, Bergman’s classification system is discussed followed by
a discussion of “neutral salts” and “metallic salts”. The green colour of hydrated
iron(II) salts was attributed to phlogiston, since it was not observed after removal of
phlogiston (oxidation to Fe
3+ ).
In the section of earths, Bergman speculated that the “heavy earth” (barium
oxide) could possibly be reduced to a metal. Scheele was of the same opinion
(Sect. 15.2), but the isolation of barium was not achieved until the nineteenth
century.
After the earths, different combustible materials were discussed: sulphur,
phosphorus, “pyrophore” (Sect. 28.5), oils, camphor, ether and charcoal. On discussing phosphorus, Bergman also discussed other phosphorescent materials such
as barium sulphide and the theory of Beccaria
4 that phosphorescence is due to
absorption of light. The discussion of ether is rather confusing and it appears that
d’Elhuyar (or the person who copied the notes) did not understand the difference
between diethyl ether and ethyl acetate. Bergman mentioned the discovery (by
Scheele, Sect. 24.8) that mineral acid is needed for the formation of ethyl acetate,
but the text suggests that ethyl acetate and diethyl ether were one and the same
compound. Bergman would not have made such an error. On discussing charcoal,
Bergman noted its similarity to coal and soot, and finally gave the recipe for an ink
suitable for marking sheep. Finally, fulminant powder (a mixture of sulphur, alkali
and potassium nitrate) and gun powder were discussed.
Bergman then turned to the metals and their characteristic properties. He discussed his investigation of the phlogiston content of metals (Sect. 22.5) and
attempted to prove that the hydrogen gas evolved by dissolving metals in acids
originates from the metal rather than from the acid.
Bergman then discussed water and heat, and stressed that water is composed of
extremely small solid particles (Sect. 22.3). Bergman gave a long discussion on
heat, and seems to adhere to Scheele’s theory that it was composed of oxygen (vital
air) and phlogiston and that light was composed of heat and phlogiston. Bergman
explained the difference between temperature and specific heat, but the latter use of
the term “specific heat” is rather confusing, and with Bergman’s background as a
physicist, it seems more likely that it is d’Elhuyar who was confused.
The last section discussed air and oxygen. He discussed the importance of
oxygen for living organisms and the effect of oxygen on blood. He also discussed
the evolution of oxygen by green plants, and assured that even toxic and
bad-smelling plants were as effective in this regard.
4
Giacomo Battista Beccaria (1716–1781). Italian physicist.
11.3 Bergman’s Lectures
171