necessary for the neutralization of the 1000 weight units of sulphuric acid are
represented. These masses are equivalent to the mass of 1000 mass units of sulphuric acid. The conclusion is evident, the substances, chemical compounds, react
mutually in the exact ratios of their masses.
The mass ratios of the substances which by the mutual reaction yield new
compounds has systematically studied Joseph Louis Proust (1754–1826), but
using the simplest, more rudimentary model. Proust has calculated the ratios of
masses of oxygen and metal (iron) which by reaction from various oxides. The
result was surprizing: similarly as it was found for neutralizations of acids with
bases, chemical elements, which by reaction form compounds, combine in the
definite ratios of their masses, the formulation that is known as Proust law.
Although well supported by experimental arguments, the law has not been
momentarily accepted in public. Claude Louis Berthollet (1748–1822), who is
known for the discovery of the chemical composition of ammonia and for the early
concept of chemical equilibrium, has rejected the idea about the constant mass
rations. At that time it was difficult to oppose the authority of Berthollet. Proust law
was finally accepted in 1811, when another authority, Jöns Jacob Berzelius, the
scientist about whom I will talk in the following lectures, has confirmed its validity.
If the exact elemental composition would be the criterion for the definition of the
identity of chemical compound, then particular chemical compound must have the
same composition independently where it is found, or by which procedure it is
prepared. Thus, its identity is independent on the way of its formation. Say, it is the
first order identity (primary identity). Chemical elements and compounds possess
their first order identity, which is independent on the history of their formation. If a
substance, or any other object obtains and changes its form during the irreversible
history, it has its individuality, the second order identity (secondary identity).
While, theoretically, the number of entities with the same first order identity could
be infinite, the second order identity belongs to only one entity, or to only one
object. For instance, crystal is such an object that possesses the second order
identity that emerges from its unique morphology, which is a consequence of the
history of its crystallization and growth—there are no two identical macroscopic
crystals. Thus, chemistry can clarify also the metaphysical categories such as
identity!
Proust has shown, that the compounds with the same elementary composition
(i.e. which have their first order identity) can appear by quite different pathways: for
instance, basic copper carbonate, which Proust has prepared in laboratory, has the
same composition and properties as the same substance found in nature, the mineral
malachite. How to explain the findings of the constant elemental composition? Is it
a consequence of the structure of microcosm?
The explanation of the nature of air has required new quantitative investigations.
Fortunately, the study of gasses includes more measurable parameters: mass, volume, pressure, and temperature. First laws that describe gasses has already
9 Atoms and Molecules
75
represented. These masses are equivalent to the mass of 1000 mass units of sulphuric acid. The conclusion is evident, the substances, chemical compounds, react
mutually in the exact ratios of their masses.
The mass ratios of the substances which by the mutual reaction yield new
compounds has systematically studied Joseph Louis Proust (1754–1826), but
using the simplest, more rudimentary model. Proust has calculated the ratios of
masses of oxygen and metal (iron) which by reaction from various oxides. The
result was surprizing: similarly as it was found for neutralizations of acids with
bases, chemical elements, which by reaction form compounds, combine in the
definite ratios of their masses, the formulation that is known as Proust law.
Although well supported by experimental arguments, the law has not been
momentarily accepted in public. Claude Louis Berthollet (1748–1822), who is
known for the discovery of the chemical composition of ammonia and for the early
concept of chemical equilibrium, has rejected the idea about the constant mass
rations. At that time it was difficult to oppose the authority of Berthollet. Proust law
was finally accepted in 1811, when another authority, Jöns Jacob Berzelius, the
scientist about whom I will talk in the following lectures, has confirmed its validity.
If the exact elemental composition would be the criterion for the definition of the
identity of chemical compound, then particular chemical compound must have the
same composition independently where it is found, or by which procedure it is
prepared. Thus, its identity is independent on the way of its formation. Say, it is the
first order identity (primary identity). Chemical elements and compounds possess
their first order identity, which is independent on the history of their formation. If a
substance, or any other object obtains and changes its form during the irreversible
history, it has its individuality, the second order identity (secondary identity).
While, theoretically, the number of entities with the same first order identity could
be infinite, the second order identity belongs to only one entity, or to only one
object. For instance, crystal is such an object that possesses the second order
identity that emerges from its unique morphology, which is a consequence of the
history of its crystallization and growth—there are no two identical macroscopic
crystals. Thus, chemistry can clarify also the metaphysical categories such as
identity!
Proust has shown, that the compounds with the same elementary composition
(i.e. which have their first order identity) can appear by quite different pathways: for
instance, basic copper carbonate, which Proust has prepared in laboratory, has the
same composition and properties as the same substance found in nature, the mineral
malachite. How to explain the findings of the constant elemental composition? Is it
a consequence of the structure of microcosm?
The explanation of the nature of air has required new quantitative investigations.
Fortunately, the study of gasses includes more measurable parameters: mass, volume, pressure, and temperature. First laws that describe gasses has already
9 Atoms and Molecules
75