352  Spirit  of  Nitrous  Ether.  \Amjl™I%m' 
THE  SPIRIT  OF  NITROUS  ETHER  OF  THE  U.  S.  P.,  1870. 
By  C.  Lewis  Diehl. 
{Read  at  the  Pharmaceutical  Meeting  of  the  Louis-ville  College  of  Pharmacy,  held  June 
7th,  1877.) 
About  eighteen  months  ago  I  had  occasion,  for  the  first  time,  to 
prepare  spirit  of  nitrous  ether  by  the  process  of  the  present  "  Pharma- 
copoeia." Operating  with  the  pharmacopoeial  quantities,  and  observing 
the  care  which  a  considerate  experience  in  the  manufacture  of  this 
product  by  the  old  method  had  taught  me,  I  obtained  results  some- 
what at  variance  with  the  requirements  and  statements  of  our  standard. 
I  have  since  had  opportunity  to  confirm  the  results  then  obtained,  and 
propose  in  this  paper  to  discuss  these,  together  with  such  additional 
observations  as  are  pertinent  to  the  subject. 
The  methods  which  have  been  proposed  from  time  to  time  for  the 
preparation  of  nitrous  ether,  or  its  medicinal  solutions,  differ  mainly  in 
the  manner  in  which  two  principal  methods  are  applied  :  the  one  pro- 
ducing nitrous  ether  by  the  direct  action  of  nitric  acid  on  alcohol  ;  the 
other  by  the  direct  action  of  nitrous  acid  on  the  same  liquid.  The 
first  named  method  is  the  older  one,  and  is  the  one  that  was  discarded 
at  the  last  revision  of  our  "  Pharmacopoeia."  The  product  of  the 
direct  action  of  nitric  acid  upon  alcohol,  irrespective  of  the  modifica- 
tion of  the  method,  always  contains,  besides  nitrous  ether,  variable 
quantities  of  acetic  and  formic  ethers,  and  aldehyd  :  the  relative 
quantities  of  these  depending  on  the  temperature,  quantities  operated 
on,  etc.  By  the  second  method — the  direct  action  of  nitrous  acid  on 
alcohol — nitrous  ether  is  formed,  it  is  claimed,  to  the  exclusion  of  the 
other  compounds,  and  this  is  the  method  applied  in  the  process  of  the 
present  "  Pharmacopoeia."  This  process,  which  is  practically  identical 
with  that  of  the  "British  Pharmacopoeia,"  was  proposed  in  1867,  by 
Professor  Theophilus  Redwood.  In  the  very  interesting  paper  in 
which  the  process  is  described,1  Professor  Redwood  reviews  the  various 
methods  that  have  at  different  times  been  suggested,  and,  among  these, 
finds  that  of  E.  Kopp  for  the  production  of  nitrous  ether  to  be,  with 
certain  modifications,  the  one  suited  to  secure  uniformlv  a  spirit  of 
definite  strength  and  purity.  Kopp's  process  consists  in  heating  a 
mixture  of  equal  volumes  of  nitric  acid,  sp.  gr.   1*36,  and  rectified 
1  "  Phar.  Jour,  and  Trans. viii,  508  5  "Am.  Jour.  Phar.,"  1867,  321. 
