of contradiction, which is the foundation not
only of physical science, but of logic in general. It means
that A can be not-A.

[F] 'Molecule' would be the more appropriate name for such a
particle. Unfortunately, chemists employ this term in a
special sense, as a name for an aggregation of their
smallest particles, for which they retain the designation of
'atoms.'

[G] 'At present more organic analyses are made in a single
day than were accomplished before Liebig's time in a whole
year.'--Hofmann, _Faraday Lecture_, p. 46.

[H] In the preface to his _Mecanique Chimique_ M. Berthelot
declares his object to be 'ramener la chimie tout entirere
... aux memes principes mecaniques qui regissent deja les
diverses branches de la physique.'

[I] This is the more curious, as Ampere's hypothesis that
vibrations of molecules, causing and caused by vibrations of
the ether, constitute heat, is discussed. See vol. ii. p.
587, 2nd ed. In the _Philosophy of the Inductive Sciences_,
2nd ed., 1847, p. 239, Whewell remarks, _a propos_ of
Bacon's definition of heat, 'that it is an expansive,
restrained motion, modified in certain ways, and exerted in
the smaller particles of the body;' that 'although the exact
nature of heat is still an obscure and controverted matter,
the science of heat now consists of many important truths;
and that to none of these truths is there any approximation
in Bacon's essay.' In point of fact, Bacon's statement,
however much open to criticism, does contain a distinct
approximation to the most important of all the truths
respecting heat which had been discovered when Whewell
wrote.

[J] Perhaps I ought rather to say Button's axiom. For that
great naturalist and writer embodied the principles of sound
geology in a pithy phrase of the _Theoris de la Terre_:
'Pour juger de ce qui est arrive, et meme de ce qui
arrivera, nous n'avons qu'a examiner ce qui arrive.'

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