324  PREPARATION  OF  SPIRIT  OF  NITROUS  ETHER. 
jected,  the  larger  is  the  proportion  of  spirit  that  may  be  present 
when  the  ether-producing  action  occurs ;  but  if  the  temperature 
be  above  200°,  the  action  is  liable  to  become  so  violent  that  much 
loss  of  product  occurs,  from  the  difficulty  of  condensing  the 
vapors,  and  from  the  more  complex  nature  of  the  reaction. 
It  has  long  been  observed;  in  making  spirit  of  nitric  ether  by 
the  London  process,  that  the  nature  of  the  product  depends,  to 
some  extent,  upon  the  quantity  of  ingredients  operated  upon, 
and  the  manner  in  which  the  heat  is  applied.  If  a  small  quantity 
of  the  mixture  be  submitted  to  distillation  in  a  retort  at  as  low 
a  temperature  as  is  sufficient  for  affecting  slow  distillation,  the 
quantity  of  distilled  product  indicated  in  the  Pharmacopoeia  may 
be  drawn  over  without  any  appreciable  amount  of  nitrous  ether 
being  formed,  so  that  the  product  in  such  case  would  be  little 
else  than  pure  spirit.  In  operating  on  larger  quantities,  how- 
ever, and  especially  in  conducting  the  process  with  a  steam- 
jacketed  still,  a  better  result  is  obtained,  the  distilled  product 
being  richer  in  ether,  in  consequence  of  the  higher  temperature 
attained  in  the  process.  But  even  in  this  case  the  result  is 
unsatisfactory,  for  not  only  is  the  amount  of  ether  produced 
small  in  relation  to  the  nitric  acid  employed,  but  most  of  the 
acid  and  much  of  the  spirit,  mixed  in  the  proper  proportion  for 
producing  ether,  would  be  left  in  the  still  as  a  waste  residue,  if 
the  process  be  stopped  at  the  point  indicated.  Practically  manu- 
facturers do  not  stop  at  this  point,  but  continue  the  distillation, 
and  thus  greatly  increase  the  strength  of  the  product.  There  is, 
nevertheless,  a  limit  beyond  which  the  distillation  cannot  be 
carried  without  great  detriment  to  the  product,  as  the  reaction 
becomes  more  and  more  complex  as  the  process  proceeds,  and 
finally  nitrous  fumes  are  abundantly  formed. 
The  nature  of  the  reaction  which  occurs  in  this  process  has 
been  investigated  by  many  able  chemists,  who  have  shown  that 
it  varies  greatly  according  to  the  conditions  present,  and  that  it 
is  very  complex,  especially  when  the  action  is  intense.  Dr. 
Golding  Bird,  many  years  ago,  and  more  recently  Dr.  Debus, 
have  contributed  to  this  investigation.  Among  the  products  of 
the  reaction,  in  addition  to  nitrous  ether  and  aldehyd,  chemists 
have  enumerated  carbonic,  formic,  acetic,  oxalic,  lactic,  saccharic 
