The regulus of manganese [manganese metal] scarcely yields to the flame; for a small
particle is easily calcined, and a large one cannot be made sufficiently hot [to melt]. The
black calx [MnO 2 ] imparts a bluish red colour to the fluxes; the tinge of borax, unless well
saturated, is more yellow. The colour may be gradually altogether destroyed by the interior
[reducing] flame, and again reproduced by a small particle of nitre, or the exterior [oxidising] flame alone; these changes may be alternated ad libitum.
As mentioned, Gahn made blow-pipe analysis his speciality. He developed such
a skill that he could detect traces of metals far below the threshold of contemporary
wet methods. Early in the nineteenth century, Berzelius befriended Gahn [50], who
taught him to use the blow-pipe. Gahn also wrote the section on blow-pipe analysis
for the second volume of Berzelius textbook [51, 52]. Later, Berzelius wrote a
300-page monograph on blow-pipe analysis [53], which was published in several
languages, the most widespread being the German editions. Towards the end of the
nineteenth century, the blow-pipe was largely replaced by emission spectroscopy,
which was easier to use and relied to a lesser extent on the skill of the analyst.
23.6 Analytical Chemistry After Bergman
Unfortunately, Bergman died in the middle of his career, and the perfection of
analytical chemistry was up to other scientists. The most famous of the next generation of analytical chemists were Kirwan, Klaproth and Vauquelin. Kirwan’s
main contribution was to simplify Bergman’s methods for water analysis and at the
same time increase the accuracy [54].
Louis Nicolas Vauquelin (1763–1829) was nearly 30 years younger than
Bergman and as an assistant of Fourcroy, he belonged to the new antiphlogistic era.
Vauquelin took up Bergman’s work on mineral analysis by wet methods, and
compared to Bergman, Vauquelin’s analytical scheme was much more elaborate
[55]. This increased the accuracy and enabled Vauquelin to discover new elements:
beryllium and chromium.
The most prominent of the analytical chemists of the late eighteenth century was,
however, Klaproth in Berlin. He was only 1 year younger than Scheele, but since
his chemical career did not actually start until the 1780s, he had no background in
the phlogiston theory. Klaproth’s main interest was mineral analysis, while he was
largely uninterested in the theoretical aspects of chemistry. He made important
contributions to the procedure of analytical chemistry, but his methods are less easy
to follow than those of Bergman; in fact he developed a specialised analytical
scheme for each mineral [55]. Klaproth introduced the practice to dry samples to
constant weight, and he reported the actual weights of his samples, and if his results
did not sum up to 100%, he always took great care to find the reason. This led to the
discovery that potassium can occur in minerals, and to the discovery of uranium,
zirconium and (independently of Berzelius and Hisinger) of cerium. Thus, his
results were much more accurate than those of Bergman. The analytical schemes
developed by Bergman and his successors are still used, with modifications to the
23.5 Bergman and the Blow-Pipe
327
particle is easily calcined, and a large one cannot be made sufficiently hot [to melt]. The
black calx [MnO 2 ] imparts a bluish red colour to the fluxes; the tinge of borax, unless well
saturated, is more yellow. The colour may be gradually altogether destroyed by the interior
[reducing] flame, and again reproduced by a small particle of nitre, or the exterior [oxidising] flame alone; these changes may be alternated ad libitum.
As mentioned, Gahn made blow-pipe analysis his speciality. He developed such
a skill that he could detect traces of metals far below the threshold of contemporary
wet methods. Early in the nineteenth century, Berzelius befriended Gahn [50], who
taught him to use the blow-pipe. Gahn also wrote the section on blow-pipe analysis
for the second volume of Berzelius textbook [51, 52]. Later, Berzelius wrote a
300-page monograph on blow-pipe analysis [53], which was published in several
languages, the most widespread being the German editions. Towards the end of the
nineteenth century, the blow-pipe was largely replaced by emission spectroscopy,
which was easier to use and relied to a lesser extent on the skill of the analyst.
23.6 Analytical Chemistry After Bergman
Unfortunately, Bergman died in the middle of his career, and the perfection of
analytical chemistry was up to other scientists. The most famous of the next generation of analytical chemists were Kirwan, Klaproth and Vauquelin. Kirwan’s
main contribution was to simplify Bergman’s methods for water analysis and at the
same time increase the accuracy [54].
Louis Nicolas Vauquelin (1763–1829) was nearly 30 years younger than
Bergman and as an assistant of Fourcroy, he belonged to the new antiphlogistic era.
Vauquelin took up Bergman’s work on mineral analysis by wet methods, and
compared to Bergman, Vauquelin’s analytical scheme was much more elaborate
[55]. This increased the accuracy and enabled Vauquelin to discover new elements:
beryllium and chromium.
The most prominent of the analytical chemists of the late eighteenth century was,
however, Klaproth in Berlin. He was only 1 year younger than Scheele, but since
his chemical career did not actually start until the 1780s, he had no background in
the phlogiston theory. Klaproth’s main interest was mineral analysis, while he was
largely uninterested in the theoretical aspects of chemistry. He made important
contributions to the procedure of analytical chemistry, but his methods are less easy
to follow than those of Bergman; in fact he developed a specialised analytical
scheme for each mineral [55]. Klaproth introduced the practice to dry samples to
constant weight, and he reported the actual weights of his samples, and if his results
did not sum up to 100%, he always took great care to find the reason. This led to the
discovery that potassium can occur in minerals, and to the discovery of uranium,
zirconium and (independently of Berzelius and Hisinger) of cerium. Thus, his
results were much more accurate than those of Bergman. The analytical schemes
developed by Bergman and his successors are still used, with modifications to the
23.5 Bergman and the Blow-Pipe
327