ON  SWEET  SPIRIT  OF  NITRE. 
253 
judge,  just  in  proportion  to  the  amount  of  AeO-fN03in  the  pre- 
paration. The  weaker  it  is,  the  better  it  keeps.  Less  acid  is 
found  in  the  fluid,  just  because  less  existed  in  it.  It  is  to  this 
proneness  to  change  that  we  ascribe  the  almost  universal  depar- 
ture from  authority,  both  as  to  modus  operandi  and  per  centage 
of  ether,  which  has  taken  place.  The  Pharmaceutical  Chemist 
cannot  make  sweet  spirit  of  nitre  in  drachms  or  half  ounces  every 
time  he  dispenses  a  prescription  containing  it.  He  must  make 
or  buy  an  article  that  will  retain  its  properties  for  at  least  a  rea- 
sonable time  ;  and  the  manufacturing  chemist  cannot  sell  an 
article  which  spoils  in  a  day  or  two,  for  no  one  will  have  it  from 
him.  Thus,  both  are  compelled  to  hunt  about  for  better  pro- 
cesses, and  not  finding  them,  either  to  give  up  making  or  selling, 
as  the  case  may  be.  Or  else  the  Pharmaceutical  Chemist  buys 
and  uses  whatever  is  offered  to  him,  asking  no  questions.  We 
have  met  with  no  specimen  which  contained  the  full  amount  of 
AeO-l-NOn,  but  we  have  met  with  it  where  it  held  internal  evi- 
dence  that  at  one  time  it  had  contained  all  it  ought.  And  we 
have  found  in  our  own  experience  that,  after  some  weeks,  a  sweet 
nitre,  originally  made  according  to  the  Edinburgh  Pharmaco- 
poeia, with  20  per  cent,  of  AeO-f-N03,  was  deficient  to  a  con- 
siderable extent,  eight  per  cent,  having  disappeared. 
The  change  which  occurs  in  sweet  spirit  of  nitre  has  been  long 
known,  and  many  endeavors  have  been  made  to  prepare  it  with- 
out this  liability.  Some,  indeed,  deny  that  this  liability  is  inhe- 
rent in  the  preparation,  and  among  others,  the  late  esteemed 
Pereira  mentioned  that  he  had  some  which  had  been  in  his  pos- 
session for  years,  "  and  which  possessed  only  slight  acidity." 
It  is  to  be  regretted  that  the  formula?  and  original  strength  of 
these  keeping  sweet  spirits  of  nitre  are  not  given.  It  is  also 
asserted  that  sweet  spirit  of  nitre  made  with  AeO-j-N03,  made 
according  to  Liebig's  process,  keeps  better  than  that  made  by 
the  ordinary  process.  So  far  as  our  experience  goes,  this  last 
assertion  is  true;  but  the  only  vehicle  we  have  found  which  will 
give  a  stable  mixture  is  absolute  alcohol — confirming  Professor 
Christison's  observations.  It  is  obvious  that  the  price  of  sweet 
spirit  of  nitre  made  with  AeO-fNo3,  procured  by  Liebig's  pro- 
cess, would  tend  to  render  its  use  very  limited  indeed.  But 
whether  it  would  or  no,  are  we  at  liberty  to  follow  that  mode  ? 
