2*8 
OK  SWEET  SPIRIT  OF  N1TRET. 
haps  justify  the  high  equivalent  which  the  author  has  attributed 
to  this  metal. 
The  author  has  also  ascertained  that  uranium  maj  also  be  ob- 
tained from  the  same  green  chloride  by  means  of  aluminium. 
Its  isolation  by  this  reaction  is  no  doubt  due  to  the  great  vola- 
tility of  the  chloride  of  aluminium. — lhid,fr&m  Oomftes-  Rendm, 
Jan.  21, 1856. 
ON  SWEET  SPIRIT  OP  NITRE. 
By  IX  R.  Broatn,  of  Edinburgh. 
It  appears  that  sweet  spirit  of  nitre  was  known  so  early  as 
the  13th  century.  It  is  at  least  something  in  its  favor,  that 
after  six  hundred  years  it  still  maintains  its  ground,  and  is  in 
very  general  use. 
An  immense  number  of  formulae-  have  been  given  for  its  pre- 
paration ;  but,  however  prepared,  it  consists  essentially  of  im- 
pure hyponitrous  ether  and  rectified  spirit,  in  variable  propor- 
tions ;  and  these  proportions  vary  from  twenty  per  cent,  of  the 
ether  down  to  one  or  even  less.  These  variations  are  not  indeed 
permitted  by  the  Colleges  of  London,  Edinburgh,  or  Dublin, 
each  having  for  itself  a  formula  for  the  preparation,  and  also  a 
standard  strength ;  yet  each  College  differs  from  all  the  others. 
The  Edinburgh  formula  gives  a  preparation  containing  20  per 
cent,  of  hyponitrous  ether,  while  that  of  the  Dublin  is  only 
8.70  per  cent.  With  respect  to  the  London  formula  it  is  difficult 
to  say  what  its  per-centage  may  be.  The  most  extravagant 
calculation  will  afford  no  more  than  16.43  per  cent.,  while  the 
reality  is  undoubtedly  much  below  this  amount.  We  have  ex- 
amined samples  of  what  was  termed  "  the  best,"  and  been  un- 
able by  fractional  distillation  to  find  more  than  a  mere  trace  ; 
among  these  were  samples  from  London.  It  is  upon  tko  presence 
of  the  ether  that  the  virtues  of  the  sweet  spirit  of  nitre  depend. 
It  is  surely  a  sad  condition  of  affairs  when  a  prescription,  written 
and  prepared  in  London  or  Dublin,  shall,  when  taken  to  Edin- 
burgh, have  the  dose  increased  to  two  doses  and  a  half ;  or,  that 
when  written  in  Edinburgh  and  prepared  in  London  or  Dublin, 
the  dose  should  go  down  to  less  than  one-half.  But  more  sad 
still,  that,  the  dose  being  either  20,  10,  or  8.7Q  per  cent,  of  the 
