copper or common salt and that wood ash (potassium carbonate) precipitates vitriol
(iron, or possibly copper sulphate) [2, 3]. Libavius
2 used wet methods for analysis
of mineral waters in the late sixteenth century. He evaporated the water samples and
investigated the shape of the crystals formed to determine their nature (alum,
saltpetre, vitriol), but he also used reagents to perform qualitative analysis in
solution: oak apple (gall nut) extract gave a black colour in the presence of iron, and
copper sulphate gave a blue colour with ammonia [4, 5]. Robert Boyle used oak
apple extract to detect iron[6] and introduced the use of sulphide solutions to
precipitate lead [5, 7]. One of Boyle’s goals was to find a reliable reagent for the
detection of arsenic.
Friedrich Hoffmann (Chap. 17) used iron to precipitate copper from water
samples, and silver nitrate to detect sodium chloride. He used vegetable extracts as
acid-base indicators to detect alkali [8, 9]. Vegetable extracts, most notably violet
extracts, were also used as acid-base indicators by Boyle in his analysis of mineral
waters [10]. In 1697, Eberhard Gockel (1636–1703) used sulphuric acid to detect
lead in wine: in the presence of lead, insoluble lead sulphate precipitated [11].
Thus, by the end of the seventeenth century, the knowledge about chemical
reactions in solution was very limited. Chemistry was mainly performed by heating,
melting, and distillation. During the eighteenth century, however, much new
knowledge was gained. One of the important figures in this field was Marggraf. He
made extensive studies on the effect of alkali carbonates on metal salt solutions
[12]. He also introduced the use of phlogisticated alkali (a solution containing
potassium cyanide and potassium hexacyanoferrate (II)) to detect iron. Another
important contribution was that he conclusively established the difference between
sodium and potassium salts [13]. Bergman was well familiar with the works of
Marggraf, which were his main source of inspiration in the development of his
analytical methods:
The illustrious Margraf [sic!] had no sooner discovered the true method of decomposition,
the humid and menstrual, than he endeavoured, by his own exertions to render it easy and
practicable. The new road into which he struck, was beset with thorns and briars; but it is
certainly the only one that leads to a knowledge of principles, both as to quality and
quantity; and therefore indispensably necessary in every enquiry into composition. [14]
Another source of inspiration may have been Scheffer, who devoted a chapter to
water analysis in his lectures [15], which Bergman published in 1775. Scheffer
made use of several reagents to qualitatively determine the constituents of water
samples; for instance, a solution of silver nitrate could be used to detect common
salt, lime could be detected with sulphuric acid, copper with ammonia and iron or
zinc with oak apple tincture.
2
Andreas Libau (1540–1616), better known as Libavius. German alchemist.
312
23 Bergman as an Analytical Chemist
(iron, or possibly copper sulphate) [2, 3]. Libavius
2 used wet methods for analysis
of mineral waters in the late sixteenth century. He evaporated the water samples and
investigated the shape of the crystals formed to determine their nature (alum,
saltpetre, vitriol), but he also used reagents to perform qualitative analysis in
solution: oak apple (gall nut) extract gave a black colour in the presence of iron, and
copper sulphate gave a blue colour with ammonia [4, 5]. Robert Boyle used oak
apple extract to detect iron[6] and introduced the use of sulphide solutions to
precipitate lead [5, 7]. One of Boyle’s goals was to find a reliable reagent for the
detection of arsenic.
Friedrich Hoffmann (Chap. 17) used iron to precipitate copper from water
samples, and silver nitrate to detect sodium chloride. He used vegetable extracts as
acid-base indicators to detect alkali [8, 9]. Vegetable extracts, most notably violet
extracts, were also used as acid-base indicators by Boyle in his analysis of mineral
waters [10]. In 1697, Eberhard Gockel (1636–1703) used sulphuric acid to detect
lead in wine: in the presence of lead, insoluble lead sulphate precipitated [11].
Thus, by the end of the seventeenth century, the knowledge about chemical
reactions in solution was very limited. Chemistry was mainly performed by heating,
melting, and distillation. During the eighteenth century, however, much new
knowledge was gained. One of the important figures in this field was Marggraf. He
made extensive studies on the effect of alkali carbonates on metal salt solutions
[12]. He also introduced the use of phlogisticated alkali (a solution containing
potassium cyanide and potassium hexacyanoferrate (II)) to detect iron. Another
important contribution was that he conclusively established the difference between
sodium and potassium salts [13]. Bergman was well familiar with the works of
Marggraf, which were his main source of inspiration in the development of his
analytical methods:
The illustrious Margraf [sic!] had no sooner discovered the true method of decomposition,
the humid and menstrual, than he endeavoured, by his own exertions to render it easy and
practicable. The new road into which he struck, was beset with thorns and briars; but it is
certainly the only one that leads to a knowledge of principles, both as to quality and
quantity; and therefore indispensably necessary in every enquiry into composition. [14]
Another source of inspiration may have been Scheffer, who devoted a chapter to
water analysis in his lectures [15], which Bergman published in 1775. Scheffer
made use of several reagents to qualitatively determine the constituents of water
samples; for instance, a solution of silver nitrate could be used to detect common
salt, lime could be detected with sulphuric acid, copper with ammonia and iron or
zinc with oak apple tincture.
2
Andreas Libau (1540–1616), better known as Libavius. German alchemist.
312
23 Bergman as an Analytical Chemist