^"FeHimL"'}         Sp.  JStheris  Nitrosi,  B.  P.  83 
viz.,  sp.  villi,  rect.  Oj.  acid  nitric  3  fluid  ounces,  acid  sulphuric  2 
fluid  ounces,  and  copper  wire.  These  ingredients  (with  the  exception 
of  J  fluid  ounce  of  the  nitric  acid  which  was  set  aside  to  be  added 
subsequently),  were  put  into  a  glass  retort,  and  the  mixture  distilled 
at  a  temperature  commencing  at  160°  and  rising  to  175°.  The  nitrous 
ether  began  to  form  at  160°,  which  is  10  degrees  lower  than  the  point 
indicated  in  the  Pharmacopoeia ;  when  the  temperature  has  risen  to 
175°  and  about  8  fluid  ounces  had  passed  over,  the  boiling  ceased,  and 
no  more  could  be  distilled  without  exceeding  the  limit  of  temperature, 
viz.,  180°  ;  so  the  contents  of  the  retort  were  allowed  to  cool  some- 
what, and  the  remaining  J  fluid  ounce  of  nitric  acid  was  added ;  the 
distillation  was  then  continued  as  before  and  3  fluid  ounces  more 
passed  over,  making  together  11  fluid  ounces  ;  a  fresh  receiver  was 
adapted  to  the  apparatus  and  the  contents  of  the  retort  heated  to  200°  ; 
the  distillate  thus  produced  measured  4J  fluid  ounces,  and  consisted 
chiefly  of  spirit ;  it  was  nearly  neutral  to  test  paper,  and  had  very 
little  flavor  of  nitrous  ether,  its  sp.  gr.  was  '867.  I  further  distilled 
the  contents  of  the  retort  until  a  temperature  of  220*^  was  shown ; 
this  produced  about  2  fluid  ounces  more  of  a  liquid,  chiefly  spirit  and 
water,  having  a  sp.  gr.  -897;  this  was  also  neutral,  but  had  a  disagree- 
able odor.  The  11  fluid  ounces  of  distillate  above  referred  to  was  then 
examined  and  found  to  have  a  sp.  gr.  -881,  and  showed  by  the  CaCl 
test  a  separation  of  42*5  per  cent.,  thus  corresponding  to  50-5  per 
cent.  C2H5NO2.  This  agrees  tolerably  well  with  the  calculated  sp.  gr. 
of  a  mixture  of  equal  parts  of  rectified  spirit  ('838)  and  nitrous  ether 
(•900),  which  gives  -870  as  a  mean  ;  the  diff'erence  between  these 
numbers  may,  I  think,  be  accounted  for  by  the  condensation  which 
takes  place  on  mixing. 
These  considerations,  I  think,  show  that  there  is  more  spirit  used 
in  the  first  part  of  the  process  than  is  necessary,  or  what  amounts  to 
the  same  thing,  too  little  nitric  acid.  I  think  a  proportionate  increase 
of  nitric  acid  should  be  used,  and  the  distillate  tested  as  to  the  amount 
of  C2H5NO2  it  contains,  and  if,  as  in  the  case  just  mentioned,  it  is 
found  to  contain  50  per  cent.,  then  1  volume  mixed  with  4  volumes  of 
rectified  spirit  would  furnish  spiritus  setheris  nitrosi  of  the  Pharma- 
copoeia strength. 
On  the  question  of  keeping  this  compound  I  regret  having  no  sug- 
gestion to  off'er.  It  seems  inherent  in  the  nature  of  nitrous  ether, 
even  when  pure,  to  change  rapidly,  becoming  strongly  acid  after  being 
