The second chapter treats the acids, which were recognised by a sour taste and
the property to turn litmus or violet syrup red. The chapter describes the three
mineral acids sulphuric acid, nitric acid and hydrochloric acid. The method of
determining the concentration of nitric acid by addition of small portions of alkali
carbonate solution until effervescence ceases [15] was a crude form of titration, and
a rare example of the use of stoichiometry before Bergman. To the three mineral
acids known to Scheffer, Bergman added hydrofluoric acid and arsenic acid discovered by Scheele (Chapter 9). Scheffer was only aware of one acid of vegetable
origin, acetic acid (vinegar), but Bergman added tartaric acid and a less known acid
(oxalic acid) present in Sal acetocellæ (potassium hydrogen oxalate, see Sect. 24.1).
He also added two acids of animal origin: phosphoric acid which was obtained from
urine and formic acid from ants. Bergman also described carbonic acid (aerial acid),
which unlike the other acids was present in all three of nature’s kingdoms. Given
Bergman’s interest in carbonic acid (Chapter 18), this section is remarkably short.
In Chapter 3, Bergman discussed the three alkalis: vegetable alkali, mineral
alkali and volatile alkali. Vegetable alkali (Alkali vegetabile) was potassium
hydroxide and potassium carbonate, which was obtained from wood ashes. Mineral
alkali (Alkali minerale) was sodium hydroxide and sodium carbonate. The main
source of sodium carbonate was deposits from soda lakes, hence the name, but it
could actually also be obtained from vegetable sources, e.g. seaweed ashes, as well,
volatile alkali (Alkali volatile), finally, was ammonia. The carbonates (fixed alkalis)
differed from the hydroxides (corrosive alkalis) in that the former were saturated
with carbonic acid (aerial acid).
The neutral salts are treated in Chapter 4. Of special interest is Bergman’s
inclusion of quantitative composition of salts (given as parts of alkali, acid and
water per 100 parts of the salt). He even gives a table of the equivalents of different
acids (sulphuric acid, nitric acid, hydrochloric acid and carbonic acid) corresponding to 100 parts of sodium- and potassium hydroxide, decades before the
more famous and influential tabulation of chemical equivalents by Ernst Gottfried
Fischer (1754–1831) in 1802 [16]. Bergman obtained his numbers by titrating the
acid solution with alkali, with a reference to Homberg [6]. Compared to Fischer’s
values, Bergman’s values were highly inaccurate (Sect. 23.2).
In Chapter 5, Bergman first discussed the salts of earths and metals with acids
and alkali. A long table of metal salts introduces his system of systematic Latin
nomenclature (Chapter 26), but without much discussion.
The second part concerns the earths. According to Scheffer, they were substances without taste or smell, and Bergman added the criterion of low solubility in
water. Four earths were known: lime (CaO), magnesia (MgO), clay (Al 2 O 3 ) and
siliceous earth (SiO 2 ). The discovery of earth of heavy spar (BaO) (Sect. 15.2) by
Scheele and Gahn is briefly mentioned in a comment. In the second chapter of part
two, the melting of earths is discussed, including the production of glass and
porcelain.
The topic of the third part is water. Neither Scheffer nor Bergman believed in the
transformation of water to earth, which had been reported by previous authors.
Bergman referred to the now famous experiment by Lavoisier, where he found that
164
11 Bergman as a Teacher
the property to turn litmus or violet syrup red. The chapter describes the three
mineral acids sulphuric acid, nitric acid and hydrochloric acid. The method of
determining the concentration of nitric acid by addition of small portions of alkali
carbonate solution until effervescence ceases [15] was a crude form of titration, and
a rare example of the use of stoichiometry before Bergman. To the three mineral
acids known to Scheffer, Bergman added hydrofluoric acid and arsenic acid discovered by Scheele (Chapter 9). Scheffer was only aware of one acid of vegetable
origin, acetic acid (vinegar), but Bergman added tartaric acid and a less known acid
(oxalic acid) present in Sal acetocellæ (potassium hydrogen oxalate, see Sect. 24.1).
He also added two acids of animal origin: phosphoric acid which was obtained from
urine and formic acid from ants. Bergman also described carbonic acid (aerial acid),
which unlike the other acids was present in all three of nature’s kingdoms. Given
Bergman’s interest in carbonic acid (Chapter 18), this section is remarkably short.
In Chapter 3, Bergman discussed the three alkalis: vegetable alkali, mineral
alkali and volatile alkali. Vegetable alkali (Alkali vegetabile) was potassium
hydroxide and potassium carbonate, which was obtained from wood ashes. Mineral
alkali (Alkali minerale) was sodium hydroxide and sodium carbonate. The main
source of sodium carbonate was deposits from soda lakes, hence the name, but it
could actually also be obtained from vegetable sources, e.g. seaweed ashes, as well,
volatile alkali (Alkali volatile), finally, was ammonia. The carbonates (fixed alkalis)
differed from the hydroxides (corrosive alkalis) in that the former were saturated
with carbonic acid (aerial acid).
The neutral salts are treated in Chapter 4. Of special interest is Bergman’s
inclusion of quantitative composition of salts (given as parts of alkali, acid and
water per 100 parts of the salt). He even gives a table of the equivalents of different
acids (sulphuric acid, nitric acid, hydrochloric acid and carbonic acid) corresponding to 100 parts of sodium- and potassium hydroxide, decades before the
more famous and influential tabulation of chemical equivalents by Ernst Gottfried
Fischer (1754–1831) in 1802 [16]. Bergman obtained his numbers by titrating the
acid solution with alkali, with a reference to Homberg [6]. Compared to Fischer’s
values, Bergman’s values were highly inaccurate (Sect. 23.2).
In Chapter 5, Bergman first discussed the salts of earths and metals with acids
and alkali. A long table of metal salts introduces his system of systematic Latin
nomenclature (Chapter 26), but without much discussion.
The second part concerns the earths. According to Scheffer, they were substances without taste or smell, and Bergman added the criterion of low solubility in
water. Four earths were known: lime (CaO), magnesia (MgO), clay (Al 2 O 3 ) and
siliceous earth (SiO 2 ). The discovery of earth of heavy spar (BaO) (Sect. 15.2) by
Scheele and Gahn is briefly mentioned in a comment. In the second chapter of part
two, the melting of earths is discussed, including the production of glass and
porcelain.
The topic of the third part is water. Neither Scheffer nor Bergman believed in the
transformation of water to earth, which had been reported by previous authors.
Bergman referred to the now famous experiment by Lavoisier, where he found that
164
11 Bergman as a Teacher