Lab
Library
Journal
Shop
Sign in
to keep
Share image
1
177
The Story of Alchemy and the Beginnings of Chemistry
·
M. M. Pattison Muir
52
The
chemist
of
to-day
places
many
compounds
in
the
same
class
because
all
are
acids,
because
all
react
similarly
under
similar
conditions.
It
used
to
be
said
that
every
acid
possesses
more
or
less
of
the
principle
of
acidity.
Lavoisier
changed
the
language
whereby
certain
facts
concerning
acids
were
expressed.
He
thought
that
experiments
proved
all
acids
to
be
compounds
of
the
element
oxygen;
and
for
many
years
after
Lavoisier,
the
alchemical
expression
the
principle
of
acidity
was
superseded
by
the
word
oxygen.
Although
Lavoisier
recognised
that
not
every
compound
of
oxygen
is
an
acid,
he
taught
that
every
acid
is
a
compound
of
oxygen.
We
know
now
that
many
acids
are
not
compounds
of
oxygen,
but
we
have
not
yet
sufficient
knowledge
to
frame
a
complete
definition
of
the
term
acid.
Nevertheless
it
is
convenient,
indeed
it
is
necessary,
to
place
together
many
compounds
which
react
similarly
under
certain
defined
conditions,
and
to
give
a
common
name
to
them
all.
The
alchemists
also
classified
substances,
but
their
classification
was
necessarily
more
vague
than
ours;
and
they
necessarily
expressed
their
reasons
for
putting
different
substances
in
the
same
class
in
a
language
which
arose
out
of
the
general
conceptions
of
natural
phenomena
which
prevailed
in
their
time.
The
primary
classification
of
substances
made
by
the
alchemists
was
expressed
by
saying;
these
substances
are
rich
in
the
principle
sulphur,
those
contain
much
of
the
principle
mercury,
and
this
class
is
marked
by
the
preponderance
of
the
principle
salt.
The
secondary
classification
of
the
alchemists
was
expressed
by
saying;
this
class
is
characterised
by
dryness,
that
by
moisture,
another
by
coldness,
and
a
fourth
by
hotness;
the
dry
substances
contain
much
of
the
element
Earth,
the
moist
substances
are
rich
in
the
element
Water,
in
the
cold
substances
the
element
Air
preponderates,
and
the
hot
substances
contain
more
of
the
element
Fire
than
of
the
other
elements.
Marker
Marker
Fine marker
White-out
Fine white-out
Circle
Paint
Unmarker
Hand
Scalpel
Dice
Sieve
Purify
Undo
Redo
Start over
