366  Spirit  of  Nitrous  Ether. 
f  Am.  Jour.  Pharm. 
t       July,  1877. 
wood's  modification  of  Kopp's  process  should  constitute  an  exception. 
To  the  contrary,  I  think  it  probable  that  small  proportions  of  by-pro- 
ducts are  formed,  and  am  strengthened  in  this  view  by  the  observation, 
that  the  final  distillate  of  the  second  experimental  distillation,  passing 
after  the  reaction  was  over,  and  being  colorless,  had  a  decided  odor  of 
formic  ether. 
I  would,  therefore,  answer  the  third  question  as  follows:  1.  The 
pharmacopoeial  statement,  that  spirit  of  nitrous  ether  contains  five  per  cent, 
of  "  its  peculiar  ether''''  is  not  correct,  if  by  "its  peculiar  ether"  absolute 
nitrous  ether  is  understood. 
2.  Conceding  that  all  of  the  nitric  acid,  used  in  the  process,  is  consumed 
in  forming  nitrous  ether  (and  all  testimony  is  in  favor  of  this  view),  the 
spirit  of  nitrous  ether  of  the  U.  S.  P.  can  not  contain  more  than  4*1766 
per  cent,  of  absolute  nitrous  ether — C±HbONOv 
IV.  Is  THE  METHOD  OF  THE  "  BRITISH  PHARM ACOPCEIA,"  POR 
DETERMINING  THE  PERCENTAGE  OF  NITROUS  ETHER  IN  THE  SPIRIT 
OF  THAT  STANDARD  RELIABLE  WITHIN  PHARMACEUTICAL  LIMITS, 
AND  CAN  IT  BE  MADE  AVAILABLE  FOR  THE  PRODUCT  OF  THE 
U.  S.  P.  ? 
In  the  foregoing  it  has  been  shown,  that  the  "Pharmacopoeia"  is  in 
error  in  some  of  its  definitions  of  the  character  of  spirit  of  nitrous 
ether,  but  that  as  regards  the  process,  it  is  in  the  main  correct.  The 
only  point  in  regard  to  the  latter  that  still  remains  in  doubt,  as  far  as 
my  experiments  are  concerned,  is  the  yield  of  distillate;  and  while  it 
seems  provable,  from  what  has  been  said,  that  the  full  quantity  of 
distillate  can  be  readily  obtained,  a  final  experiment  can  alone  determine 
this  satisfactorily.  That  the  process  itself  is  a  good  one  admits  of  no 
doubt.  It  is  readily  executed  and,  if  due  precautions  are  observed,  all 
of  the  nitric  acid  used  is  represented  in  the  product  as  nitrous  ether. 
Nevertheless  it  is  desirable  that  some  controlling  test  should  be  applied 
to  the  product,  since,  under  ordinary  conditions,  a  portion  of  ether  may 
be  lost,  and  the  spirit  become  correspondingly  deficient.  It  occured  to 
me,  therefore,  to  determine  if  the  method  of  the  "  British  Phamaco- 
poeia  "  for  determining  the  strength  of  its  spirit  was  sufficiently  reliable, 
and,  if  so,  how  it  could  best  be  applied  to  the  product  of  our  "  Phar- 
macopoeia." This  method  has  already  been  alluded  to,  and  is  based 
upon  the  fact,  that   when  an  alcoholic  solution  of  nitrous  ether  is 
