Before
effective
____________________
,
surgery
was
very
____________________
and
very
painful
.
Before
1800
,
alcohol
and
____________________
had
little
success
in
easing
pain
during
operations
.
Laughing
gas
was
used
in
1844
in
dentistry
in
the
USA
,
but
failed
to
ease
all
pain
and
patients
____________________
conscious
.
Ether
(
used
from
1846
)
made
patients
totally
unconscious
and
lasted
a
long
time
.
However
,
____________________
could
make
patients
____________________
during
operations
and
sick
afterwards
.
It
was
highly
flammable
and
was
____________________
in
heavy
glass
bottles
.
Chloroform
(
used
from
1847
)
was
very
effective
with
few
side
effects
.
However
,
it
was
difficult
to
get
the
dose
right
and
could
kill
some
people
____________________
of
the
effect
on
their
heart
.
An
____________________
helped
to
regulate
the
dosage
.
