60         ON  SPIRITUS  ETHERIS  NITROSI  AND  NITRIC  ETHER. 
that  the  employment  of  copper  cuttings,  recommended  by  Kopp, 
was  serviceable,  and  gives  the  following  directions  for  the  prepara- 
tion of  the  officinal  ether. 
Twenty-four  ounces  of  spirit  of  wine,  specific  gravity,  .833, 
are  mixed  with  the  same  quantity  of  nitric  acid,  specific  gravity 
1.2,  and  then  4  ounces  of  copper  cuttings  are  added.  From  the 
mixture  24  ounces  are  drawn  over,  which  are  mixed  with  a  little 
tincture  of  litmus,  and  a  solution  of  soda  or  potash  is  added 
gradually,  until  the  distillate  acquires  a  blue  color.  From  this 
distillate  8  ounces  are  now  drawn  over  and  mixed  with  16  of  the 
strongest  spirits  of  wine,  by  which  the  product  equals  the  quan- 
tity of  spirits  originally  used.  The  preparation  thus  obtained 
free  from  acid  should  be  kept  in  two  or  three  ounce  bottles  quite 
full.  This  spirit  of  nitric  ether  is  of  a  slight  yellow  color,  ex- 
tremely powerful,  and  of  a  pure  odor,  and  in  all  cases  more  so 
than  pure  spirit  of  wine. 
The  Prussian  Pharmacopoeia  requires  a  spirit  of  nitric  of 
specific  gravity  .820 — .825.  This  is  a  great  error,  because,  in 
consequence,  the  spirit  of  nitre  is  unquestionably  deteriorated. 
When  the  pharmaceutist  obtains  a  product  which  has  not  this 
specific  gravity,  he  can  only  produce  it  by  the  addition  of  strong 
spirit,  by  which  the  contents  of  nitric  ether  are  diminished. 
Further,  when,  according  to  the  Pharmacopoeia,  nitric  acid, 
diluted  with  eight  times  its  quantity  of  alcohol,  is  distilled,  pure 
spirit  of  wine  at  first  passes  over,  and  only  towards  the  end  the 
yellow  strongly  odorous  product  comes  over.  But,  on  the  con- 
trary, when  the  distillate  is  rectified,  the  latter  goes  over  at  first, 
and  the  spirit  of  wine  at  last ;  therefore  it  is  incomprehensible 
why  the  Pharmacopoeia  directs  the  first  ounce  to  be  rejected. 
From  these  circumstances,  Mohr  concludes  that  it  is  very  fal- 
lacious to  remove  the  small  quantity  of  free  acid,  which  the  ether  t 
always  exhibits  after  a  time,  by  repeated  rectification,  as  the 
changes  which  spirit  of  nitre  thereby  undergoes  occasion  much 
more  evil  consequence  than  that  which  arises  from  the  presence 
of  a  little  free  acid. 
In  the  officinal  spirit  of  nitre,  the  nitric  ether  is  obtained 
mixed  with  alcohol  and  water.  In  the  distillate  obtained  from 
copper  so  much  nitric  ether  is  obtained,  that  when  this  is  once 
rectified,  and  one-third  drawn  over,  from  this  third  part  the 
