298 
SPIRITUS  iETHEBIS  NITRICI. 
turned  to  the  retort,  the  carbonate  of  potassa  added  to  it,  the 
whole  shaken  round  well  without  splashing  into  the  retort  neck, 
the  apparatus  connected,  and  the  warm  water  of  the  bath  care- 
fully and  slowly  applied  so  that  the  distillation  does  not  exceed 
the  capacity  of  the  condenser.  This  capacity  is  easily  and 
nicely  determined  by  watching  the  drop  which  always  occupies 
the  end  of  the  small  eduction  tube  fitted  to  the  end  of  the  con- 
denser. If  the  condenser  is  working  below  its  capacity,  bubbles 
of  air  will  from  time  to  time  pass  into  the  apparatus,  and  the 
delivery  will  be  irregular  from  this  tendency  of  air  to  pass  in  by 
or  through  the  condensed  liquid.  If  working  beyond  its  capa- 
city the  drops  will  be  blown  out  by  escaping  vapors.  The  first 
part  of  the  rectification  should  not  proceed  too  slowly,  however, 
for  the  distillate  then,  from  being  nearly  pure  ether,  evaporates 
rapidly,  particularly  if  received  in  a  large  mouthed  vessel. 
As  a  guide  to  the  strength  of  the  preparation,  it  is  proper  to 
notice  that  about  1  f.5  should  pass  over  before  the  temperature 
of  the  boiling  liquid  rises  above  150°,  and  that  by  the  time  the 
temperature  reaches  176°  3  f.5  should  have  been  received  This 
3  f.3  of  distillate  should  have  a  s.  g.  of  -869. 
The  rectification  is  carried  to  6  f.g,  and  this  distillate  is  di- 
luted to  19 J  f.§  with  the  remainder  of  the  alcohol,  and  well  sha- 
ken. It  should  then  be  transferred  at  once  to  small  bottles 
well  filled  and  stopped,  and  covered  with  dark  wrappers. 
If  the  first  distillate  be  rectified  fractionally,  it  will  yield  as 
follows : 
1  f.§  up  to  15?'°  golden  yellow  s.  g.  -8944  at  54° 
1  f.3     «     173°  paler       «        «     -8640  «  60° 
1  f.5     «     176°  paler       «        «    -8483  «  60° 
giving  a  mean  s.  g.  for  the  first  3  f.5  of  -869.    The  remaining 
3  f.5  is  nearly  colorless,  and  almost  wholly  alcohol. 
Assuming  that  the  first  3  f.g  is  a  solution  of  hyponitrous  ether 
in  alcohol,  it  will  consist  of  7-94  f.5"  of  the  ether  ond  16-03  f.5 
of  alcohol,  and  will  therefore  yield  a  finished  preparation  con- 
taining 5-1  per  cent,  of  dry  hyponitrous  ether. 
I  have  found  in  practice  that  nitric  acid  which  is  sold  as 
"  142"  s.  g.  commonly  has  a  true  s.  g.  of  1-405  to  1-41,  and 
the  commercial  acid  sold  as  "  1-38  "  is  often  as  low  as  1-35  in 
reality.    So  alcohol  sold  as  "  -835  "  is  rarely  below  -838  and 
