SPTRITUS  2ETHERIS  NITRICI. 
297 
Take  of  Nitric  Acid,  s.  g.  1408  2f.g. 
(or      «      «       «      1-35       2|  f.5) 
Alcohol,        «      -835  22Jf.§) 
(or        «  «      -838       21  f.*) 
Carbonate  of  Potassa,  2g' 
The  apparatus  being  set  up,  add  the  nitric  acid  slowly  to  9  f.g  of 
the  alcohol  in  the  retort,  and  having  the  thermometer  in  place,  ap- 
ply the  heat.  The  mixing  of  the  materials  gives  them  a  tempera- 
ture of  93°  to  commence  with.  If  the  nitric  acid  used  is  nearly 
colorless  the  mixture  will  be  colorless  also  till  heated  to  near  the 
boiling  point,  when  it  becomes  yellow. 
It  begins  to  boil  at  179°  to  181°  and  boils  and  distils  ac- 
tively at  184Q,  yielding  a  yellow  distillate  from  the  first.  It 
occasionally  happens  that  this  in  common  with  many  other  liquids, 
boils  badly,  becoming  heated  far  above  the  boiling  point,  and 
only  boiling  at  intervals  and  by  bursts  of  ebullition.  This  curious 
condition  of  fluids  commonly  occurs  in  small  round  bottomed 
glass  vessels,  and  may  be  measurably  controlled  by  having  a 
fragment  or  two  of  glass  in  the  retort.  These  should  not  be 
dropped  in  while  the  liquid  is  heated  above  its  boiling  point,  as 
they  then  almost  invariably  cause  it  to  boil  over,  but  the  pro- 
cess should  always  commence  with  this  simple  precaution. 
The  mixture  goes  on  boiling  and  distilling  steadily  at  a  tem- 
perature gradually  and  slowly  rising  to  186Q  or  137°  where  it  be- 
comes stationary  till  7  f.  J  of  distillate  has  passed  over.  The  heat 
is  then  moderated  by  lowering  the  lamp  till  the  temperature  falls 
to  176Q,  and  the  distillation  continued  about  this  point  till  the 
distillate  amounts  to  8  f.g.  when  the  first  part  of  the  process  is 
terminated. 
During  this  distillation  the  temperature  is  liable  to  fall  sudden- 
ly a  degree  or  more,  and  then  slowly  rise  again,  such  variations 
of  temperature  may  be  disregarded  as  long  as  the  rate  of  distilla- 
tion continues  unchanged ;  but  if  coincidently  with  a  fall  of 
temperature  the  distillation  should  increase  and  gases  pass  over 
uncondensed,  the  lamp  should  be  at  once  removed.  The  tem- 
perature will  then  continue  to  fall  steadily  to  170°  while  the 
distillation  slackens,  when  the  heating  may  be  cautiously  resumed 
till  the  prescribed  8  f.g  has  been  received  below  176° 
The  apparatus  is  then  thoroughly  rinsed  out,  the  distillate  re- 
