Am.  Jour.  Pharm  ) 
July,  1877.  J 
Spirit  of  Nitrous  Ether. 
353 
spirit  in  contact  with  copper  filings,  and,  when  chemical  action  has 
commenced,  withdrawing  the  heat  and  allowing  the  distillation  to  go 
on  spontaneously.  The  process,  however,  whiie  well  suited  for  the 
preparation  of  nitrous  ether,  is  wasteful  and,  consequently,  expensive  ; 
while,  at  the  same  time,  the  reaction  does  not  proceed  with  the  desired 
regularity.  After  numerous  experiments,  Professor  Redwood  found 
that  by  the  introduction  of  certain  proportions  of  sulphuric  acid,  the 
complete  utilization  of  the  nitric  acid  for  the  formation  of  nitrous 
ether,  with  a  minimum  consumption  of  copper,  could  be  secured,  and 
that  the  reaction  took  place  with  the  utmost  regularity.  The  propor- 
tions found  to  work  best,  and  these  have  been  retained  without  change 
in  the  "  British  Pharmacopoeia,"  are  : 
Nitric  acid,  sp.  gr.  142,  .  .  .3  fluidounces 
Sulphuric  acid,  sp.  gr.  1*843,  •  •  2  " 
Copper,  in  fine  wire  (about  No.  25),  .  .       2  ounces 
Rectified  spirit  (for  the  reaction),         .  .  20  fluidounces 
Rectified  spirit  (for  diluting  the  distillate),  .  .        2  pints 
Professor  Redwood's  directions  for  manipulating  these  ingredients 
have  been  adopted  verbatim  in  the  "  British  Pharmacopoeia,"  and  out- 
own  standard  has  essentially  adopted  the  same  directions  ;  hence  it  is 
not  necessary  to  reproduce  them  here.  He  further  explains,  that  at  a 
temperature  of  I50°F.  bubbles  begin  to  rise  in  the  liquid  in  the  retort ; 
that  these  increase  to  i70°F.,  when  ether  begins  to  form,  and  that 
when  it  reaches  I75°F.  the  reaction  proceeds  rapidly  and  steadily  until 
the  nitric  acid  is  all  expended,  without  any  further  rise  in  temperature 
if  the  heat  is  properly  adjusted.  The  completion  of  the  process  is 
indicated  by  the  dissappearance  of  the  froth — which  is  caused  by 
chemical  reaction,  and  not  by  boiling — and  the  distillate  will  then 
amount  to  about  12  fluidounces.  The  remaining  one-half  fluidounce 
of  nitric  acid  is  added  "  for  the  purpose  of  converting  the  undecom- 
posed  spirit  still  in  the  retort  into  nitrous  ether."  The  15  fluidounces 
of  distillate  contain  35  per  cent,  of  crude  ether.  When  mixed  with 
the  remaining  two  pints  of  spirit,  a  product  results  which  has  a  sp. 
gr.  of  0*845,  and  when  mixed  with  twice  its  volume  of  concentrated 
solution  of  chloride  of  calcium,  separates  from  two  to  three  per  cent, 
of  nitrous  ether.  This  indicates  ten  per  cent,  of  ether  [crude  ?],  as 
eight  per  cent,  remain  in  solution. 
Comparing  now  the  process  of  the  United  States  with  that  of  the 
23 
