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
123
The
breathing
of
animals
and
the
burning
of
substances
were
supposed
to
load
the
atmosphere
with
phlogiston.
Priestley
spoke
of
the
atmosphere
as
being
constantly
"vitiated,"
"rendered
noxious,"
"depraved,"
or
"corrupted"
by
processes
of
respiration
and
combustion;
he
called
those
processes
whereby
the
atmosphere
is
restored
to
its
original
condition
(or
"depurated,"
as
he
said),
"dephlogisticating
processes."
As
he
had
obtained
his
dephlogisticated
air
by
heating
the
calx
of
mercury,
that
is
the
powder
produced
by
calcining
mercury
in
the
air,
Priestley
was
forced
to
suppose
that
the
calcination
of
mercury
in
the
air
must
be
a
more
complex
occurrence
than
merely
the
expulsion
of
phlogiston
from
the
mercury:
for,
if
the
process
consisted
only
in
the
expulsion
of
phlogiston,
how
could
heating
what
remained
produce
exceedingly
pure
ordinary
air?
It
seemed
necessary
to
suppose
that
not
only
was
phlogiston
expelled
from
mercury
during
calcination,
but
that
the
mercury
also
imbibed
some
portion,
and
that
the
purest
portion,
of
the
surrounding
air.
Priestley
did
not,
however,
go
so
far
as
this;
he
was
content
to
suppose
that
in
some
way,
which
he
did
not
explain,
the
process
of
calcination
resulted
in
the
loss
of
phlogiston
by
the
mercury,
and
the
gain,
by
the
dephlogisticated
mercury,
of
the
property
of
yielding
exceedingly
pure
or
dephlogisticated
air
when
it
was
heated
very
strongly.
Priestley
thought
of
properties
in
much
the
same
way
as
the
alchemists
thought
of
them,
as
wrappings,
or
coverings
of
an
essential
something,
from
which
they
can
be
removed
and
around
which
they
can
again
be
placed.
The
protean
principle
of
phlogiston
was
always
at
hand,
and,
by
skilful
management,
was
ready
to
adapt
itself
to
any
facts.
Before
the
phenomena
of
combustion
could
be
described
accurately,
it
was
necessary
to
do
two
things;
to
ignore
the
theory
of
phlogiston,
and
to
weigh
and
measure
all
the
substances
which
take
part
in
some
selected
processes
of
burning.
Marker
Marker
Fine marker
White-out
Fine white-out
Circle
Paint
Unmarker
Hand
Scalpel
Dice
Sieve
Purify
Undo
Redo
Start over
