SPXRXTUS  iETHEEJS  NITRICI. 
295 
long  axis.  The  comparative  freedom  from  aldchyd,  for  it  is  never 
altogether  free  from  it,  is  an  indication  of  the  care  and  success 
with  which  the  process  has  been  conducted,  and  is,  too,  an  indica- 
tion of  the  length  of  time  the  preparation  will  keep  in  dispensing. 
Put  up  as  above  directed,  this  preparation  has  kept  for  one  year 
without  the  slightest  appreciable  change.  How  much  longer  it 
will  keep,  I  am  not  able  to  say  at  present. 
If,  in  the  rectification  of  the  above  product,  the  distillation  be 
conducted  fractionally  and  the  different  portions  of  the  distillate 
examined,  they  will  be  found  nearly  as  follows  : — 
18  f-5  received  up  to  150°  golden  yellow,    s.  g.  -900  at  50° 
2|  i.%       «         «     160Q  pale  straw,  «    -878  «  57^ 
6|  tl       «       at      160°  paler    "  «    -869  «  56° 
10  f.5        "      up  to  176°    "       "  not  examined. 
The  last  portion,  not  examined,  probably  contains  1\  of 
ether,  of  s.  g.  -869,  at  least,  in  which  case  a  calculation  by  the 
specific  gravities  indicates  that  this  preparation  contains  very 
nearly  14  f.5  of  dry  hyponitrous  ether,  s.  g.  -947,  or  about  5-1 
per  cent. 
In  adopting  the  proportions  of  this  formula  I  supposed  it  would 
yield  a  preparation  medicinally  identical  with  that  of  the  U.  S.  P. 
process,  and  this  supposition,  based  upon  a  practical  observation 
in  making  nitric  acid,  was  strengthened  by  the  physical  proper- 
ties of  the  resulting  spirit  of  nitre.  I  have  since  found,  how- 
ever, as  now  stated,  that  the  18  J  5  of  nitric  acid  of  s.  g.  1-408 
that  the  United  States  Pharmacopoeia  materials  do  yield  when 
distilled  separately  is  not  utilized  in  that  process,  for  if  the 
ready  made  acid  in  this  quantity  is  substituted  for  the  materials 
for  generating  it,  the  yield  of  ether  is  over  1  per  cent,  more  in 
the  preparation.  The  U.  S.  P.  process  should  yield  a  prepara- 
tion containing  5  per  cent,  of  dry  ether,  but  cannot  be  made  to 
do  so  in  my  hands  except  by  obtaining  the  nitric  acid  as  a  sepa- 
rate operation.  Why  the  acid  yields  one  fourth  more  ether 
than  I  can  obtain  in  using  the  materials  for  generating  it,  I 
could  only  attempt  to  explain  upon  theoretical  grounds,  which  I 
do  not  fully  entertain  in  opposition  to  the  practical  experience 
upon  which  the  Pharmacopoeia  process  is  based. 
This  process  of  obtaining  a  dilute  hyponitrous  ether,  and 
then  farther  diluting  it,  is  quite  applicable  to  general  pharma- 
