'^'"janriso^"^'}  Preparation  of  Spirit  of  Nitrous  Ether,  7 
THE  PREPARATION  OF  SPIRIT  OF  NITROUS  ETHER. 
By  R.  F.  Fairthorne,  Ph.G. 
Read  at  the  Pharmaceutical  Meeting  December  15. 
Amongst  other  members  of  the  committee  on  the  revision  of  the 
Pharmacopoeia,  having  the  duty  assigned  to  me  of  revievi^ing  that  class 
of  substances  in  which  spirit  of  nitrous  ether  is  included,  I  w^ould 
respectfully  make  a  few  suggestions.  The  uncertainty  of  strength  of 
sweet  spirit  of  nitre,  as  made  by  the  officinal  formula,  owing  chiefly, 
perhaps,  to  the  extreme  volatility  of  nitrous  ether  and  the  difficulty  of 
determining  its  etherial  strength,  make  it  desirable  that  a  process  should 
be  devised  by  which  such  uncertainty  should  be  avoided,  and  I  would 
propose  the  following  as  meeting  these  requirements,  namely  :  First, 
to  make  the  nitrous  ether,  which  I  accomplish  without  the  use  of  heat 
or  distillation  ;  then  to  mix  5  parts  of  this  with  95  parts  of  alcohol,  so 
as  to  have  a  preparation  of  definite  composition  in  accordance  with  the 
supposed  strength  of  the  article,  as  made  by  the  present  formula. 
If  5  parts,  by  weight,  of  nitric  acid,  of  specific  gravity  1*36,  are 
mixed  with  4  parts  of  alcohol,  of  specific  gravity  -822,  both  liquids 
having,  previous  to  mixing,  been  reduced  to  the  temperature  of 
6o°F.,  no  perceptible  action  takes  place.  To  this  is  added  a  small 
portion  of  starch  (30  grains  to  9  ounces  of  the  mixture),  and  the  whole 
placed  in  a  deep  cylindrical  vessel,  in  which  the  liquids  would  occupy 
about  one-sixth  of  its  capacity.  If  the  vessel  is  then  set  aside  in  a 
cool  place,  the  temperature  of  which  is  above  the  freezing  point  but 
below  6o°F.,  in  two  or  three  days  the  liquid  will  be  found  divided  into 
two  distinct  layers,  the  upper  one  being  impure  nitrous  ether.  This  is 
removed  by  means  of  a  funnel  havir.g  a  stop-cock  in  the  neck,  and 
after  ^pouring  it  into  a  four-ounce  well -stoppered  vial,  it  is  agitated 
first  with  3  per  cent,  of  calcined  magnesia,  and  to  the  mixture  is  added 
8  per  cent,  of  stronger  solution  of  ammonia,  and  well  shaken ;  the 
upper  layer  of  liquid,  which  is  the  purified  nitrous  ether,  is  filtered 
through  cotton,  moderately  packed  in  a  funnel,  and  then  weighed.  To 
every  100  parts,  by  weight,  are  added  1900  parts  of  alcohol,  of  specific 
gravity  '822.  By  this  treatment  of  the  crude  nitrous  ether,  both  free 
acid  and  aldehyd  are  removed,  the  first  by  the  magnesia  and  the  last  by 
the  ammonia,  which  has  a  strong  affinity  for  it. 
In  order  to  succeed  with  this  process  it  is  necessary  to  bear  in  mind 
that  the  ether  is  extremely  volatile  (boiling  between  61  and  62°F.),  and 
