silver precipitated with zinc has a very high zinc content and effervesces with
hydrochloric acid.
The use of silver had the advantage that the precipitated silver flakes off the
analysed metal fairly well and the mixture can be mechanically separated (unlike
copper that forms a crust on the metal). Even so, the author of this book found it
difficult, even in a modern laboratory, to obtain much more accurate values for the
atomic weight of copper than Bergman did using his method.
References
1. Scheele CW (1777) Chemische Abhandlung von der Luft und dem Feuer, M Swederus & S.
L Crusius, Uppsala & Leipzig, p 1
2. Scheele CW (1780) Chemical Observations and Experiments on Air and Fire. J. Johnson,
London, p 2
3. Scheele CW (1777) Chemische Abhandlung von der Luft und dem Feuer. M. Swederus,
Uppsala and Leipzig, p 86
4. Bergman T (1781) Tilläggning om Tungsten KVA Nya Handl 2:95–98
5. Bergman T (1779) Anledning til föreläsningar öfver chemiens beskaffenhet och nytta, samt
naturliga kroppars almännaste skiljaktigheter, M. Swederus, Stockholm, Uppsala and Åbo,
p 39
6. Gadolin J (1789) Undersökning, huruvida Brunsten kan förvandlas i Kalkjord. KVA Nya
Handl 10:141–150
7. Cassebaum H, Kauffman GB (1776) The Analytical Concept of a Chemical Element in the
Work of Bergman and Scheele, Ann Sci 33:447–45
8. Bergman T (1779) Anledning til föreläsningar öfver chemiens beskaffenhet och nytta, samt
naturliga kroppars almännaste skiljaktigheter, M. Swederus, Stocholm, Uppsala & Åbo, p 2
Table 22.1 Results of Bergman’s determination of equivalent weights
Metal
a
“Equivalents” of
silver
b
Corresponding atomic
weight
c
Modern atomic
weight
Hg
74
292
200.59
Pb
43
502
207.2
Cu
323
66.8
63.55
Fe
342
63.1
55.85
Sn
114
119
118.71
Ni
156
138
58.69
Co
270
79.9
63.55
Zn
182
98,2
65.39
Mn
196
110
54.94
a Bi, Sb and As have been excluded, since these elements have a more complex behaviour in
solution
b
The amount of silver precipitated by 100 parts of the metal
c Atomic weight of the metal calculated assuming the metal is oxidised to M
2+ and the atomic
weight of silver is set to 107.87 u
22.5 Phlogiston Content of Metals—Determination of Equivalent Weights
309
hydrochloric acid.
The use of silver had the advantage that the precipitated silver flakes off the
analysed metal fairly well and the mixture can be mechanically separated (unlike
copper that forms a crust on the metal). Even so, the author of this book found it
difficult, even in a modern laboratory, to obtain much more accurate values for the
atomic weight of copper than Bergman did using his method.
References
1. Scheele CW (1777) Chemische Abhandlung von der Luft und dem Feuer, M Swederus & S.
L Crusius, Uppsala & Leipzig, p 1
2. Scheele CW (1780) Chemical Observations and Experiments on Air and Fire. J. Johnson,
London, p 2
3. Scheele CW (1777) Chemische Abhandlung von der Luft und dem Feuer. M. Swederus,
Uppsala and Leipzig, p 86
4. Bergman T (1781) Tilläggning om Tungsten KVA Nya Handl 2:95–98
5. Bergman T (1779) Anledning til föreläsningar öfver chemiens beskaffenhet och nytta, samt
naturliga kroppars almännaste skiljaktigheter, M. Swederus, Stockholm, Uppsala and Åbo,
p 39
6. Gadolin J (1789) Undersökning, huruvida Brunsten kan förvandlas i Kalkjord. KVA Nya
Handl 10:141–150
7. Cassebaum H, Kauffman GB (1776) The Analytical Concept of a Chemical Element in the
Work of Bergman and Scheele, Ann Sci 33:447–45
8. Bergman T (1779) Anledning til föreläsningar öfver chemiens beskaffenhet och nytta, samt
naturliga kroppars almännaste skiljaktigheter, M. Swederus, Stocholm, Uppsala & Åbo, p 2
Table 22.1 Results of Bergman’s determination of equivalent weights
Metal
a
“Equivalents” of
silver
b
Corresponding atomic
weight
c
Modern atomic
weight
Hg
74
292
200.59
Pb
43
502
207.2
Cu
323
66.8
63.55
Fe
342
63.1
55.85
Sn
114
119
118.71
Ni
156
138
58.69
Co
270
79.9
63.55
Zn
182
98,2
65.39
Mn
196
110
54.94
a Bi, Sb and As have been excluded, since these elements have a more complex behaviour in
solution
b
The amount of silver precipitated by 100 parts of the metal
c Atomic weight of the metal calculated assuming the metal is oxidised to M
2+ and the atomic
weight of silver is set to 107.87 u
22.5 Phlogiston Content of Metals—Determination of Equivalent Weights
309