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177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
143
When
the
student
of
chemistry
desires
to
effect
the
transformation
of
one
definite
substance
into
another,
he
is
told
to
determine,
by
quantitative
experiments,
what
are
the
elements,
and
what
the
quantities
of
these
elements,
which
compose
the
compound
which
he
proposes
to
change,
and
the
compound
into
which
he
proposes
to
change
it;
and
he
is
given
working
definitions
of
the
words
element
and
compound.
If
the
compound
he
desires
to
produce
is
found
to
be
composed
of
elements
different
from
those
which
form
the
compound
wherewith
his
operations
begin,
he
is
directed
to
bring
about
a
reaction,
or
a
series
of
reactions,
between
the
compound
which
is
to
be
changed,
and
some
other
collocation
of
elements
the
composition
of
which
is
known
to
be
such
that
it
can
supply
the
new
elements
which
are
needed
for
the
production
of
the
new
compound.
Since
Lavoisier
realised,
for
himself,
and
those
who
were
to
come
after
him,
the
meaning
of
the
terms
element
and
compound,
we
may
say
that
chemists
have
been
able
to
form
a
mental
picture
of
the
change
from
one
definite
substance
to
another,
which
is
clear,
suggestive,
and
consistent,
because
it
is
an
approximately
accurate
description
of
the
facts
discovered
by
careful
and
penetrative
investigations.
This
presentment
of
the
change
has
been
substituted
for
the
alchemical
conception,
which
was
an
attempt
to
express
what
introspection
and
reasoning
on
the
results
of
superficial
investigations,
guided
by
specious
analogies,
suggested
ought
to
be
the
facts.
Lavoisier
was
the
man
who
made
possible
the
more
accurate,
and
more
far-reaching,
description
of
the
changes
which
result
in
the
production
of
substances
very
unlike
those
which
are
changed;
and
he
did
this
by
experimentally
analysing
the
conceptions
of
the
element
and
the
compound,
giving
definite
and
workable
meanings
to
these
conceptions,
and
establishing,
on
an
experimental
foundation,
the
generalisation
that
the
sum
of
the
quantities
of
the
substances
which
take
part
in
any
change
is
itself
unchanged.
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