330  PREPARATION  OP  SPIRIT  OF  NITROUS  ETHER. 
Take  of  Nitric  Acid,  sp.  gr.  1*42,        '         3  fluid-ounces. 
Sulphuric  Acid,  sp.  gr.  1-843,  2  fluid-ounces. 
Copper,  in  fine  wire  (about  No.  25,)  2  ounces. 
Rectified  Spirit,  3  pints. 
To  one  pint  of  the  spirit  add  gradually  the  sulphuric  acid, 
stirring  them  together  ;  then  add,  in  the  same  way,  2 J  fluid- 
ounces  of  the  nitric  acid.  Put  the  mixture  into  a  retort  or  other 
suitable  apparatus,  in  which  the  copper  has  been  introduced,  and 
to  which  a  thermometer  is  fitted.  Attach  now  an  efficient  con- 
denser, and  applying  a  gentle  heat,  let  the  spirit  distil  at  a  temp- 
erature commencing  at  170°  Fahr.,  and  rising  to  175°,  but  not 
exceeding  180°,  until  12  fluid-ounces  have  passed  over  and  been 
collected  in  a  bottle  kept  cool,  if  necessary  with  ice-cold  water ; 
then  withdraw  the  heat,  and  having  allowed  the  contents  of  the 
retort  to  cool,  introduce  the  remaining  half-ounce  of  nitric  acid, 
and  resume  the  distillation  as  before,  until  the  distilled  product 
has  been  increased  to  15  fluid-ounces.  Finally,  mix  this  with 
the  remaining  two  pints  of  spirit. 
In  this  process,  when  the  heat  has  been  applied,  and  the  temp- 
erature of  the  liquid  has  reached  about  150°,  numerous  minute 
bubbles  of  gas  are  observed  to  issue  from  the  surface  of  the  cop- 
per, and  these  increase  until  the  temperature  has  reached  170°, 
when  nitrous  ether  begins  to  be  formed,  and  the  liquid,  at  the 
same  time,  becomes  colored  with  a  salt  of  copper.  The  tempera- 
ture now  quickly  rises  to  175°,  at  which,  if  the  heat  applied  to 
the  retort  be  properly  adjusted,  it  will  remain  with  scarcely  any 
variation  throughout  the  process.  At  the  temperature  of  175° 
the  distillation  proceeds  rapidly  and  steadily,  the  surface  of  the 
liquid  in  the  retort  being  covered  with  a  froth  of  about  half  an 
inch  in  thickness,  and  the  space  above  it  being  filled  with  a 
transparent  vapor  of  a  yellowish  color.  This  color  is  not  due  to 
the  presence  of  nitrous  fumes,  but  appears  to  be  that  of  the 
ethereal  vapor.  The  effervescence  in  the  liquid  is  evidently  not 
that  of  ebullition,  but  of  chemical  action,  and  this  does  not  alter 
either  in  its  nature  or  intensity,  the  distilled  product  continuing 
unchanged  from  first  to  last.  I  have  never  found  it  necessary 
to  alter  the  source  of  heat  while  the  distillation  is  proceeding  if 
it  be  properly  adjusted  at  the  commencement,  and  the  process 
