PREPARATION  OF  SPIRIT  OF  NITROUS  ETHER. 
329 
it  is  acted  upon  at  the  end  of  the  process,  I  thought  there  might 
be  an  advantage  in  substituting  some  other  organic  body  of  a 
similar  description  that  would  be  soluble  in  the  spirit.  Grape 
sugar  and  glycerine  were  thus  tried,  but  with  no  better  success 
than  was  obtained  with  starch.  In  using  glycerine,  however,  a 
practical  difficulty  was  experienced  ;  it  was  found  almost  impos- 
sible to  distil  a  mixture  of  nitric  acid,  spirit,  and  glycerine  in  a 
glass  vessel,  on  account  of  the  violent  bumping  which  takes 
place,  and  which  endangers  the  safety  of  the  apparatus.  In  this 
respect,  therefore,  glycerine  produces  an  effect  the  reverse  of 
that  produced  by  starch. 
Finding  that  of  all  the  reducing  agents  tried,  copper  was  that 
which  acted  in  the  most  satisfactory  manner,  I  returned  to  it, 
and  endeavored  to  overcome  the  objections  that  had  presented 
themselves  to  its  use.  My  object  was  not  to  produce  pure  nitrous 
ether,  but  good  sweet  spirit  of  nitre,  and  therefore  the  quantity 
of  spirit  required  for  this  purpose  was  used.  I  found  that  in  dis- 
tilling a  mixture  of  nitric  acid  and  spirit  in  contact  with  copper, 
if  the  proportion  of  spirit  to  the  acid  was  more  than  one  to  five 
by  volume,  the  copper  was  but  slightly  acted  upon  ;  and  here,  as 
in  the  other  cases  noticed,  the  formation  of  nitrous  ether  did  not 
take  place  to  any  appreciable  extent  until  the  proportion  of  acid 
to  spirit  was  reduced  to  about  one  volume  to  four.  The  process 
then  proceeded  with  great  regularity,  the  proportion  of  ether  in 
the  distillate  increasing  as  the  liquid  in  the  retort  became  more 
highly  charged  with  nitric  acid  ;  but  it  was  only  during  one  short 
period  of  the  process  that  the  best  result  occurred,  and  with  this 
exception  the  distillation  yielded  little  else  than  pure  spirit.  In 
endeavoring  to  equalize  the  action  and  diffuse  it  through  the  en- 
tire process  I  tried  the  effect  of  adding  a  portion  of  sulphuric 
acid  to  the  other  ingredients,  and  in  this  way  I  completely  ac- 
complished the  object. 
After  a  great  many  trials,  in  which  the  ingredients  were  used 
in  different  proportions,  I  adopted  the  following  process  as  one 
in  every  way  suited  for  the  production  of  spirit  of  nitrous  ether, 
equal  in  strength  and  similar  in  composition  to  that  described  in 
the  British  Pharmacopoeia  : — 
