structure. Works of Mitscherlich and Wöhler are complementary, while
Mitscherlich has demonstrated that different substances can have the same structure
(observed as the same form of crystals), Wöhler has shown that the same elemental
composition can have substances with their different structure. Such an abstract
notion of structure has been reached by starting from two independent approaches.
However, the category of structure has slowly transformed in more realistic
form, i.e. it was re-defined as a way in which atoms are interconnected with each
other: the constitution.
It could be speculated, that Berzelius has possibly in mind these experiments
when he introduced the notion of isomer, the substance that possesses the same
elemental composition, but the different constitution.
Thanks to Berzelius, two new important concepts of structural theory, composition and constitution, were introduced in chemistry. Composition, the quantitative
elemental content of the measured mass ratios of elements, determines the number
of atoms of particular element in the compound in agreement with the Dalton’s
theory of atoms. However, as I have shown in the example with water, the accurate
composition is possible to determine only if we have the exact values of the relative
atomic masses. Application of Mitscherlich analogies was limited with the relatively small number of isomorphic crystals. The solution of this problem is either in
finding new criteria for analogy, or to obtain the relative atomic masses in another
way. Berzelius has succeeded to determine the relative atomic masses relatively
accurately, within the possibilities of measuring at that time. As a reference value,
Berzelius has used the mass of oxygen instead the mass of hydrogen. Indeed, the
Berzelius values are not very far from the relative atomic masses that we use today.
Already from phlogiston theory and Lavoisier revolution, the problem of the
substances of animal and plant origin has remained unsolved, because none of these
theories were able to comprise this question. Particular chemical behaviour of the
substances of plant and animal origin has been reflected in the emergence of the
vitalistic thinking, by which chemistry in living systems is different from the
chemistry in inorganic world. Jöns Jacob Berzelius, as a convinced vitalist, has
deserved his work to chemistry of organic compounds. His experience in experimentation with the compounds isolated from living beings Berzelius has applied to
the systematic examination of elemental compositions of organic substances. Since
organic substances burn by producing water and carbon dioxide, Berzelius has
succeeded to calculate compositions of organic compounds from the measured
masses of these products of combustion. Starting with the atomic masses, which he
has determined, Berzelius has not only calculated compositions, but also developed
the symbolism that represents it. As symbols for elements, Berzelius has used one
or two letters of their Latin names, and the number of atoms in the chemical
compound is labelled with the numeric indexes above the letter:
10 Systematization, Classification, Structure, and Elements
83
Mitscherlich has demonstrated that different substances can have the same structure
(observed as the same form of crystals), Wöhler has shown that the same elemental
composition can have substances with their different structure. Such an abstract
notion of structure has been reached by starting from two independent approaches.
However, the category of structure has slowly transformed in more realistic
form, i.e. it was re-defined as a way in which atoms are interconnected with each
other: the constitution.
It could be speculated, that Berzelius has possibly in mind these experiments
when he introduced the notion of isomer, the substance that possesses the same
elemental composition, but the different constitution.
Thanks to Berzelius, two new important concepts of structural theory, composition and constitution, were introduced in chemistry. Composition, the quantitative
elemental content of the measured mass ratios of elements, determines the number
of atoms of particular element in the compound in agreement with the Dalton’s
theory of atoms. However, as I have shown in the example with water, the accurate
composition is possible to determine only if we have the exact values of the relative
atomic masses. Application of Mitscherlich analogies was limited with the relatively small number of isomorphic crystals. The solution of this problem is either in
finding new criteria for analogy, or to obtain the relative atomic masses in another
way. Berzelius has succeeded to determine the relative atomic masses relatively
accurately, within the possibilities of measuring at that time. As a reference value,
Berzelius has used the mass of oxygen instead the mass of hydrogen. Indeed, the
Berzelius values are not very far from the relative atomic masses that we use today.
Already from phlogiston theory and Lavoisier revolution, the problem of the
substances of animal and plant origin has remained unsolved, because none of these
theories were able to comprise this question. Particular chemical behaviour of the
substances of plant and animal origin has been reflected in the emergence of the
vitalistic thinking, by which chemistry in living systems is different from the
chemistry in inorganic world. Jöns Jacob Berzelius, as a convinced vitalist, has
deserved his work to chemistry of organic compounds. His experience in experimentation with the compounds isolated from living beings Berzelius has applied to
the systematic examination of elemental compositions of organic substances. Since
organic substances burn by producing water and carbon dioxide, Berzelius has
succeeded to calculate compositions of organic compounds from the measured
masses of these products of combustion. Starting with the atomic masses, which he
has determined, Berzelius has not only calculated compositions, but also developed
the symbolism that represents it. As symbols for elements, Berzelius has used one
or two letters of their Latin names, and the number of atoms in the chemical
compound is labelled with the numeric indexes above the letter:
10 Systematization, Classification, Structure, and Elements
83