356     SPIRIT  OF  NITROUS  ETHER  AND  NITRITE  OF  SODA. 
in  sand,  first  with  a  gentle  heat,  and  afterwards  with  a  stronger, 
to  driness.  §  5.  The  receiver  let  be  very  large,  and  the  neck 
of  the  retort  fit  for  it,  and  so  enter  a  good  way  in,  and  the  junc- 
ture to  be  well  luted,  for  otherwise  you  will  lose  much  of  your 
spirit.  §  6.  It  is  necessary  that  the  spirit  should  be  cohobated 
twice  at  least,  some  authors  advice  thrice  ;  for  the  oftener  it  is 
cohobated  the  sweeter  it  is.  §  12.  In  this  mixture  the  spirit  of 
nitre  joyns  itself  to  the  sulphur  of  the  wine,  and  both  being  ad- 
mirably volatile,  they  strive  to  mount  upwards,  whereby  the 
mixture  is  put  into  that  mighty  motion  and  effervescency  ;  and 
from  whence  results  a  complicate  spirit,  being  most  fragrant, 
and  having  the  greatest  volatility.  §  14.  Rolfincius,  in  Chemia, 
lib.  3,  sec.  1,  art.  4,  cap.  11,  advises  after  four  days  digestion 
to  distil  it  in  an  alembick,  so,  says  he,  will  the  spirits  in  this 
operation  be  united,  and  contract  a  violet  kind  of  odor  or  smell, 
and  a  subdulce  and  grateful  taste." 
Now  this  process,  of  acting  upon  spirit  of  wine  by  nitric  acid, 
has  been  handed  down  in  the  various  editions  of  our  Pharmaco- 
poeias with  very  little  alteration,  except  in  the  employment  of 
more  definite  materials,  until  within  comparatively  a  few  years 
since.  The  nitric  acid  and  rectified  spirit  have  varied  in 
the  proportions  in  the  different  Pharmacopoeias,  from  one  of 
acid  and  three  of  spirit  to  one  of  acid  and  seventeen  and  a  quar- 
ter of  spirit.  The  product  has  been  variously  designated  as 
spiritus  nitri  dulcis,  spiritus  setheris  nitrosi,  spiritus  aetheris 
nitrici,  spiritus  sethereus  nitrosus  ;  the  more  common  commercial 
terms,  however,  have  been,  spirit  of  nitre,  sweet  spirit  of  nitre,  or 
sometimes  simply  nitre. 
In  1826  the  Dublin  College  introduced  nitrous  ether  into  their 
list  of  preparations.  The  process  consisted  in  submitting  to  dis- 
tillation a  mixture  of  dry  nitrate  of  potash  24  oz.,  of  strong  sul- 
phuric acid  16  oz.,  and  rectified  spirit  19  fl.  oz.  The  acid  and 
spirit  being  first  mixed  together  and  allowed  to  cool  before  addi- 
tion to  the  nitrate  of  potash.  The  distillation  is  ordered  to  be 
slowly  and  carefully  conducted,  and  the  uncondensed  vapors 
passed  into  another  vessel  through  16  oz.  of  spirit  kept  cold. 
This  ethereal  liquid  is  then  to  be  purified  by  agitation  with  dry 
carbonate  of  potash.  If  required  very  pure  it  is  to  be  redistilled 
