148  Note  on  Amylo-Niirous  EtJier.  {^^TimT' 
proaches  boiling,  the  fire  is  removed  and  the  reaction  allowed  to  con- 
tinue. If  the  application  of  the  heat  has  been  too  rapid  or  too  long 
continued,  considerable  frothing  occurs  and  the  contents  of  the  retort 
are  apt  to  foam  over.  With  a  moderate  and  slowly  increased  heat, 
the  reaction  is  less  violent  and  the  temperature  rises  gradually,  after 
the  removal  of  the  fire  and  the  beginning  of  boiling.  As  soon  as  the 
thermometer,  inserted  into  the  tubulus,  rises  above  100*^  C.  (212°  F.) 
the  receiver  is  changed,  the  distillate  now  becoming  more  and  more 
mixed  with  ethyl-amylic  ether  and  nitrate  of  amyl,  readily  perceived 
by  the  change  in  odor. 
The  distillate  obtained  below  100°  C.  is  now  agitated  with  an  aque- 
ous solution  of  caustic  or  carbonate  of  potassa,  to  remove  free  acids, 
and  after  separation  the  oily  liquid  is  introduced  into  a  clean  retort 
and  again  slowly  heated.  The  first  portion  coming  over  contains  the 
amylic  aldehyde.  When  the  very  slowly  increased  heat  has  risen  to 
96°  C,  the  receiver  is  again  changed  and  the  distillate  now  collected 
as  nitrite  of  amyl,  until  the  thermometer  reaches  100°  C,  when  the 
distillation  is  stopped. 
It  will  be  observed  that  the  process  for  the  preparation  of  this  com- 
pound consists  of  two  distinct  operations  :  first,  the  production  of  the 
amyl-nitrous  ether,  and,  secondly,  its  purification.  In  both  opera- 
tions the  very  gradual  application  and  increase  of  heat  is  very  essen- 
tial. The  yield  is  small;  not  having  kept  any  record  of  the  yield,  I 
am  unable  to  give  she  per  centage  obtained.  All  the  araylo-nitrous 
ether  dispensed  by  me  was  made  by  this  process. 
After  the  publication  of  Redwood's  process  for  spirit  of  nitrous 
ether,*  it  was  repeatedly  tried  with  entirely  satisfactory  results,  and 
the  idea  naturally  suggested  itself  to  apply  the  same  process  to  the 
similar  compound  amylo-nitrous  ether.  Accordingly  amylic  alcohol 
was  mixed  with  sulphuric  acid,  the  mixture  introduced  into  a  retort 
together  with  some  copper  wire,  and,  after  cooling,  nitric  acid  was 
added.  In  a  very  few  moments  the  evolutipn  of  gas  was  observed, 
the  liquid  became  hot  without  the  external  application  of  heat,  an(J 
the  reaction  very  rapidly  increased  to  such  a  violence  that  the  entire 
charge  was  lost,  it  being  impossible  to  condense  any  vapors  in  a  Lie- 
big's  condenser,  or  to  retain  much  of  the  liquid  forced  over,  in  the 
receiver.    The  experiment  was  never  repeated. 
*  See  Amer.  Jour.  Pharm.,  1867,  p.  330. 
