Am.  Jour.  Pharm.\ 
July,  1897.  J 
Liquefaction  of  Fluorine. 
367 
Gladstone's  experiments  on  atomic  refraction6  can  well  be  com- 
pared with  these  facts. 
In  fact  fluorine  by  certain  of  its  properties  resembles  oxygen, 
though  at  the  same  time  it  is  distinctly  at  the  head  of  the  chlorine 
group. 
The  conclusion  to  be  drawn  from  these  observations  appears  to 
be  that  fluorine  can  only  be  liquefied  with  great  difficulty.  One  of 
us  showed  that  at  a  temperature  of  —  95°,  at  the  ordinary  pressure, 
there  is  no  change  at  all.7 
In  the  new  experiments  which  we  now  publish,  fluorine  was  pre- 
pared by  the  electrolysis  of  fluoride  of  potassium  in  solution  in 
anhydrous  hydrofluoric  acid.  The  fluorine  gas  was  freed  from  vapors 
of  hydrofluoric  acid,  by  being  passed  through  a  serpentine  of  plati- 
num, cooled  by  a  mixture  of  solid  carbonic  acid  and  alcohol. 
Two  platinum  tubes  filled  with  perfectly  dry  fluoride  of  sodium  com- 
pleted the  purification. 
The  apparatus  used  for  liquefying  this  gas  consisted  of  a  small 
cylinder  of  thin  glass,  to  the  upper  part  of  which  was  fused  a  plati- 
num tube.  This  latter  contained  in  its  axis  another  smaller  tube, 
likewise  of  platinum.  The  gas  to  be  liquefied  enters  by  the  annular 
space,  passes  through  the  glass  envelope,  and  escapes  through  the 
smaller  inner  tube.  This  apparatus  was  fused  to  the  tube  by  which 
the  fluorine  was  supplied. 
In  these  experiments  we  used  liquid  oxygen  as  the  refrigerant. 
It  was  prepared  according  to  the  method  already  described  by  one 
of  us,  and  this  research,  we  may  remark,  required  several  litres.8 
The  apparatus  being  cooled  down  to  the  temperature  of  quietly 
boiling  liquid  oxygen  (183°),  the  current  of  fluorine  gas  passed 
through  the  glass  envelope  without  becoming  liquid.  But  at  this 
low  temperature  it  has  lost  its  chemical  activity,  and  no  longer 
attacks  the  glass. 
If  we  now  make  a  vacuum  over  the  oxygen,  we  see,  as  soon  as 
rapid  ebullition  takes  place,  a  liquid  collecting  in  the  glass  envelope, 
6 J.  H.  Gladstone  and  G.  Gladstone,  "Refraction  and  Dispersion  of  Fluoben- 
zine  and  Allied  Compounds,"  Phil.  Mag.,  Series  5,  Vol.  XXXI,  p.  1. 
7  H.  Moissan,  "Nouvelles  Recherckes  sur  le  Fluor,"  Ann.  de  Chim.  et  de 
Pkys.,  Series  6,  Vol.  XXIV,  p.  224. 
8 J.  Dewar,  "New  Researches  on  Liquid  Air,"  Royal  Institution  of  Great 
Britain,  1896,  and  Proc.  Roy.  Inst.,  1893. 
