Am.  Jour.  Pharm.l 
August,  raoo.  / 
Gasometric  Analysis. 
367 
perforation  of  the  cork,  serves  as  a  syphon  when  the  apparatus  is 
filled,  and  also  supports  the  small  funnel ;  the  outer  end  of  this  tube 
should  be  bent  upwards  or  else  fused  to  decrease  the  diameter  so  as 
to  prevent  air  from  entering  and  displacing  the  brine.  Another 
vial,  or,  better,  a  graduate  or  graduated  cylinder,  is  used  to  collect 
the  displaced  fluid. 
ESTIMATION    OF   SPIRIT    OF    NITROUS  ETHER. 
To  prepare  the  apparatus  for  use  almost  fill  the  bottle  with  a 
saturated  brine,  close  with  stopper  and  place  syphon-tube  in  a  ves- 
sel containing  brine ;  then,  while  pressing  together  the  rubber  tub- 
ing about  the  small  glass  plug  to  form  a  small  channel  between  the 
latter  and  the  tubing,  apply  suction  by  mouth  at  the  small  funnel 
Fig.  i. — Apparatus  for  the  Estimation  of  Spirit  of  Nitrous  Ether. 
until  the  latter  is  partly  filled  with  brine  when  the  tubing  is 
released  ;  it  will  be  found  that  all  air  has  been  removed  from  the 
bottle  and  tubing  below  the  plug  (should  a  bubble  or  so  be  found 
below  the  cork  a  little  manipulation  will  cause  it  to  enter  the  glass 
tube,  and  it  can  then  be  withdrawn  by  suction  after  compressing 
the  tubing).  The  apparatus  is  now  to  be  adjusted  to  zero;  this 
simply  means  allowing  the  brine,  by  compressing  the  rubber  tubing 
at  a,  to  flow  out  of  the  syphon-tube  until  the  brine  in  the  funnel 
stands  level  or  even  with  the  upper  end  of  the  rubber  tubing.  Re- 
place the  vessel  containing  the  brine  by  the  graduated  glass,  and 
you  are  ready  for  the  assay.    Allow  5  c.c.  sweet  spirit  of  nitre  to 
