^^Gas. Citazioni.
Gas simplicity (Maxwell)
Gases are distinguished from other forms of matter, not only by their power
of indefinite expansion so as to fill any vessel, however large, and by the
great effect heat has in dilating them, but by the uniformity and simplicity of
the laws which regulate these changes.
— James Clerk Maxwell
Theory of Heat (1904), 31.
ref:
http://www.todayinsci.com
Gas compounds (Gay-Lussac)
Compounds of gaseous substances with each other are always formed in very
simple ratios, so that representing one of the terms by unity, the other is 1,
2, or at most 3 ... The apparent contraction of volume suffered by gas on
combination is also very simply related to the volume of one of them.
— Joseph Louis Gay-Lussac
Mémoires de la Société d' Arcueil, 1809, 2, 233-4. Trans. Foundations of the
Molecular Theory, Alembic Club Reprint, no. 4 (1950), 24.
ref:
Gas-Quotations.htm
Gas are made of atoms (Ostwald)
I am now convinced that we have recently become possessed of experimental
evidence of the discrete or grained nature of matter, which the atomic
hypothesis sought in vain for hundreds and thousands of years. The isolation and
counting of gaseous ions, on the one hand, which have crowned with success the
long and brilliant researches of J.J. Thomson, and, on the other, agreement of
the Brownian movement with the requirements of the kinetic hypothesis,
established by many investigators and most conclusively by J. Perrin, justify
the most cautious scientist in now speaking of the experimental proof of the
atomic nature of matter, The atomic hypothesis is thus raised to the position of
a scientifically well-founded theory, and can claim a place in a text-book
intended for use as an introduction to the present state of our knowledge of
General Chemistry.
—
Wilhelm OstwaldIn Grundriss der allgemeinen Chemie (4th ed.,
1909), Preface, as cited by Erwin N. Hiebert and Hans-Gunther Korber in article
on Ostwald in Charles Coulston Gillespie (ed.), Dictionary of Scientific
Biography Supplement 1, Vol 15-16, 464.
Statistical mechanics (Ludwig Boltzmann)
We must make the following remark: a proof, that after a certain time t1,
the spheres must necessarily be mixed uniformly, whatever may be the initial
distribution of states, cannot be given. This is in fact a consequence of
probability theory, for any non-uniform distribution of states, no matter how
improbable it may be, is still not absolutely impossible. Indeed it is clear
that any individual uniform distribution, which might arise after a certain time
from some particular initial state, is just as improbable as an individual
non-uniform distribution; just as in the game of Lotto, any individual set of
five numbers is as improbable as the set 1, 2, 3, 4, 5. It is only because there
are many more uniform distributions than non-uniform ones that the distribution
of states will become uniform in the course of time. One therefore cannot prove
that, whatever may be the positions and velocities of the spheres at the
beginning, the distributions must become uniform after a long time; rather one
can only prove that infinitely many more initial states will lead to a uniform
one after a definite length of time than to a non-uniform one. Loschmidt's
theorem tells us only about initial states which actually lead to a very
non-uniform distribution of states after a certain time t1;
but it does not prove that there are not infinitely many more initial conditions
that will lead to a uniform distribution after the same time. On the contrary,
it follows from the theorem itself that, since there are infinitely many more
uniform distributions, the number of states which lead to uniform distributions
after a certain time t1, is much greater than the number that
leads to non-uniform ones, and the latter are the ones that must be chosen,
according to Loschmidt, in order to obtain a non-uniform distribution at t1.
—
Ludwig Eduard Boltzmann
'On the Relation of a General Mechanical Theorem to the Second Law of
Thermodynamics' (1877), in Stephen G. Brush (ed.), Selected Readings in
Physics (1966), Vol. 2, Irreversible Processes, 191-2.