SPIRITUS  iETIIERIS  NITRICI. 
299 
often  above  '838,  whilst  I  have  not  yet  seen  a  specimen  of  «  95 
per  cent  "  alcohol  that  was  in  reality  below  «8195  to  «820  s.  g. 
If  the  second  set  of  proportions  given  in  brackets  in  the  for- 
mula, be  used  with  these  commercial  materials  that  are  not 
weaker  than  the  specific  gravities  given  indicate,  the  mixture 
will  boil  at  180Q  but  the  boiling  point  will  not  rise  so  high  as 
186°  till  near  the  end  of  the  distillation.  Then  however  it  is 
prone  to  rise  higher  and  to  produce  more  aldehyd  in  the  distil- 
late if  not  very  carefully  and  slowly  conducted.  The  same 
quantity  8  f.^  should  be  distilled  over,  and  at  similar  temper- 
atures. In  the  rectification  about  7  f.3  will  pass  over  below 
150°  to  156°,  and  3  f.g  below  176°.  The  rectification  should 
be  carried  to  5  f.§  only,  and  to  this  should  be  added  11  f.^  of 
alcohol,  making  1  pint  of  finished  sweet  spirit  of  nitre. 
The  s.  g.  of  the  20  f.S  first  received  in  the  rectification  is  -8732 
which  yields  by  calculation  6-94  f.z  of  the  ether  s.  g.  -947  and 
13-06  f.o  of  alcohol  s.  g.  -838,  thus  furnishing  a  product  con- 
taining 5-2  per  cent,  of  the  dry  ether,  or  practically  the  same 
with  the  other  materials. 
This  preparation  cannot  be  distinguished  from  the  other  by 
appearance  or  sensible  properties,  is  neutral  to  test  paper,  but 
has  a  very  different  s.  g. — .8  VI  instead  of  .8415— and  is  liable  to 
contain  more  aldehyd.  Of  its  keeping  properties  I  can  say  noth- 
ing, only  that  I  believe  that  sweet  spirit  of  nitre  keeps  best 
when  it  contains  least  water  ;  and  that  much  water  will  cause  it 
to  spoil  very  soon,  no  matter  how  carefully  it  may  be  kept. 
Except  that  ordinary  nitric  acid  is  almost  as  liable  to  con- 
tain chlorine,  as  nitrate  of  potassa  is  to  contain  chlorides,  the  first 
of  these  processes  on  the  small  scale  is  nearly  unobjectionable  in 
practice,  chiefly  because  the  proportions  of  acid  and  alcohol  are 
such  that  etherification  occurs  near  the  boiling  point  of  the  mix- 
ture, and  near  the  boiling  point  of  alcohol,  where  the  temperature 
is  most  easily  regulated.  It  avoids  the  violent  reaction  and 
difficult  management  of  the  Edinburgh  and  Dublin  processes,  and 
also  avoids  the  loss  attending  the  separation  and  manipulation 
of  so  volatile  a  liquid  as  these  processes  obtain,  for  as  the  alcohol 
distils  over  with  the  ether,  and  as  the  ether  is  slowly  produced, 
its  volatilization  or  loss  is  measurably  controlled. 
When  the  alcohol  bears  a  smaller  proportion,  to  the  acid  than 
