A History of Science, vol 4 | Page 4

physicist attempted to
reveal the very nature of matter and of energy, we have now to seek the
solution of the yet more inscrutable problems of life and of mind.
I. THE PHLOGISTON THEORY IN CHEMISTRY
The development of the science of chemistry from the "science" of
alchemy is a striking example of the complete revolution in the attitude
of observers in the field of science. As has been pointed out in a
preceding chapter, the alchemist, having a preconceived idea of how
things should be, made all his experiments to prove his preconceived

theory; while the chemist reverses this attitude of mind and bases his
conceptions on the results of his laboratory experiments. In short,
chemistry is what alchemy never could be, an inductive science. But
this transition from one point of view to an exactly opposite one was
necessarily a very slow process. Ideas that have held undisputed sway
over the minds of succeeding generations for hundreds of years cannot
be overthrown in a moment, unless the agent of such an overthrow be
so obvious that it cannot be challenged. The rudimentary chemistry that
overthrew alchemy had nothing so obvious and palpable.
The great first step was the substitution of the one principle, phlogiston,
for the three principles, salt, sulphur, and mercury. We have seen how
the experiment of burning or calcining such a metal as lead "destroyed"
the lead as such, leaving an entirely different substance in its place, and
how the original metal could be restored by the addition of wheat to the
calcined product. To the alchemist this was "mortification" and
"revivification" of the metal. For, as pointed out by Paracelsus,
"anything that could be killed by man could also be revivified by him,
although this was not possible to the things killed by God." The
burning of such substances as wood, wax, oil, etc., was also looked
upon as the same "killing" process, and the fact that the alchemist was
unable to revivify them was regarded as simply the lack of skill on his
part, and in no wise affecting the theory itself.
But the iconoclastic spirit, if not the acceptance of all the teachings, of
the great Paracelsus had been gradually taking root among the better
class of alchemists, and about the middle of the seventeenth century
Robert Boyle (1626-1691) called attention to the possibility of making
a wrong deduction from the phenomenon of the calcination of the
metals, because of a very important factor, the action of the air, which
was generally overlooked. And he urged his colleagues of the
laboratories to give greater heed to certain other phenomena that might
pass unnoticed in the ordinary calcinating process. In his work, The
Sceptical Chemist, he showed the reasons for doubting the threefold
constitution of matter; and in his General History of the Air advanced
some novel and carefully studied theories as to the composition of the
atmosphere. This was an important step, and although Boyle is not

directly responsible for the phlogiston theory, it is probable that his
experiments on the atmosphere influenced considerably the real
founders, Becker and Stahl.
Boyle gave very definitely his idea of how he thought air might be
composed. "I conjecture that the atmospherical air consists of three
different kinds of corpuscles," he says; "the first, those numberless
particles which, in the form of vapors or dry exhalations, ascend from
the earth, water, minerals, vegetables, animals, etc.; in a word,
whatever substances are elevated by the celestial or subterraneal heat,
and thence diffused into the atmosphere. The second may be yet more
subtle, and consist of those exceedingly minute atoms, the magnetical
effluvia of the earth, with other innumerable particles sent out from the
bodies of the celestial luminaries, and causing, by their influence, the
idea of light in us. The third sort is its characteristic and essential
property, I mean permanently elastic parts. Various hypotheses may be
framed relating to the structure of these later particles of the air. They
might be resembled to the springs of watches, coiled up and
endeavoring to restore themselves; to wool, which, being compressed,
has an elastic force; to slender wires of different substances,
consistencies, lengths, and thickness; in greater curls or less, near to, or
remote from each other, etc., yet all continuing springy, expansible, and
compressible. Lastly, they may also be compared to the thin shavings
of different kinds of wood, various in their lengths, breadth, and
thickness. And this, perhaps, will seem the most eligible hypothesis,
because it, in some measure, illustrates the production of the elastic
particles we are considering. For no art or curious instruments are
required to make these shavings whose curls are in no wise uniform,
but seemingly casual; and what is more remarkable, bodies that before
seemed unelastic, as beams and blocks, will afford