80 The Poetry of Physics and The Physics of Poetry
In the absence of any empirical information regarding the structure
of matter, the Baconian-Cartesian controversy over the existence of
atoms was for a long time a philosophical one. The resolution of this
question of physics was finally achieved by a chemist. John Dalton,
whose interpretation of certain empirical laws of chemical combination
provided the first observational evidence for the existence of atoms.
Dalton’s work is the first example we shall encounter, which demon-
strates the intimate connection between chemistry and physics. This
should be no surprise for according to our definition of physics as the
study of nature, it is obvious that the distinction between physics and
chemistry is artificial and is a result of historic accident. The same may
be said of the division between astronomy and physics. Just as Newton’s
theory of motion and gravitation displayed the unity of astronomy and
physics so has the concept of the atom united chemistry and physics.
Chemistry grew out of the art of alchemy, a practice that has been
somewhat maligned in modern times. The alchemists attacked the
problem of converting the base metals into gold. The reason their
practice has been maligned is that a number of the assumptions that
formed the basis of their work have subsequently been shown to be
incorrect and hence the alchemists were engaged in a futile attempt
to convert the base metals into gold. They believed like many of the
early Greeks and Mesopotamians that earth, water, air and fire were
the basic elements out of which all things in this world are made. To this
list they added two other elements — mercury, which they claimed
imparts metallic qualities to substances and sulfur, which produces
inflammability. They regarded metals as compounds of the elements fire,
and earth, a natural assumption on the basis of their observations. Metals
such as iron and copper were produced by reducing metallic ore in a very
hot fire, hence they thought a metal was a compound of mercury and
earth (the ore) and fire. In actuality iron ore is a compound of iron,
oxygen and impurities, which under the conditions of extreme heat
reduces to pure iron. This was unknown to the alchemist, however, who
hoped that by adding more fire or perhaps mercury and sulphur or all
three to a metal like lead or iron they would be able to produce gold.
It is unfair to be critical of their attempt to alter the metallic elements
chemically when they did not realize that the metals of iron, lead,
mercury and copper were basic elements. Although they never succeeded
in obtaining their goal they established the experimental foundation of
modern chemistry. In fact the boundary between alchemy and chemistry