PREPARATION  OP  SPIRIT  OF  NITROUS  ETHER.  323 
temperature  had  reached  195°.  The  action  was  not  so  intense 
as  in  the  previous  experiment,  and  therefore  the  heat  of  the  lamp 
was  not  withdrawn,  but  the  flame  was  lowered.  The  tempera- 
ture of  the  liquid  in  the  retort  rose  to  200°,  but  afterwards  fell 
to  185°,  without  any  alteration  in  the  source  of  heat ;  at  this 
temperature  ether  came  over  freely,  but  without  altering  the 
flame  of  the  lamp  the  heat  of  the  liquid  in  the  retort  rose  to  195° 
before  the  action  ceased.  The  distilled  product  amounted  to  two 
and  a  half  fluid-ounces,  and  the  residue  in  the  retort  to  seven 
fluid-drachms. 
3.  A  mixture  of  one  fluid-ounce  of  nitric  acid  and  five  fluid- 
ounces  of  spirit  was  submitted  to  distillation  as  in  the  previous 
experiment.  When  the  temperature  had  risen  to  185°,  spirit 
began  to  pass  over  without  any  ether.  The  temperature  gradu- 
ally increased  to  205°,  with  irregular  ebullition,  but  still  nothing 
but  spirit  passed  over.  The  irregularity  of  the  ebullition  caused 
the  temperature  to  vary  between  200°  and  205°,  and  this  con- 
tinued until  six  fluid-drachms  of  spirit  had  distilled,  when  chemi- 
cal action  commenced,  and  ether  began  to  appear  in  the  distilled 
product.  The  temperature  now  rose  to  208°,  and  the  action  be- 
came so  violent  that  much  of  the  vapor  escaped  uncondensed. 
As  the  process  proceeded,  however,  the  temperature  fell,  and  the 
action  then  became  more  regular  and  satisfactory.  The  result 
was  that  the  total  distilled  product  amounted  to  three  and  a  half 
fluid-ounces,  while  seven  fluid-drachms  of  liquid  were  left  in  the 
retort. 
These  experiments  show  that  when  a  mixture  of  nitric  acid 
and  spirit  is  submitted  to  distillation,  as  it  usually  is  in  the  pre- 
paration of  sweet  spirit  of  nitre,  the  proportion  of  spirit  greatly 
exceeding  that  at  which  chemical  action  occurs  and  ether  is  pro- 
duced, the  first  part  of  the  process  consists  in  the  simple  distil- 
lation of  alcohol ;  and  when  this  has  been  carried  so  far  that  the 
spirit  which  remains  in  the  retort  is  about  four  times  the  volume 
of  the  acid,  ether  begins  to  be  formed.  The  exact  proportion  of 
acid  and  spirit  required  for  the  production  of  ether  depends  upon 
the  temperature  at  which  they  are  brought  into  contact  with  each 
other,  as  will  be  seen  from  a  comparison  of  experiments  2  and 
3.    The  higher  the  temperature  to  which  the  mixture  is  sub- 
