i86 
Liquefaction  of  Gases. 
J  Am.  Jour.  Pharm„ 
(      April,  1878. 
The  liquefaction  of  one  of  the  hitherto  so  called  "  incoercible  "  gases 
having  been  accomplished,  it  was  followed  before  the  close  of  the  year 
by  similar  results  obtained  by  Cailletet  with  the  remaining  two,  nitro- 
gen and  hydrogen,  the  latter  of  which  was  solidified  by  Pictet  January 
9;  atmospheric  air  has  likewise  been  liquefied.  The  following  descrip- 
tion of  the  apparatus  with  which  these  results  were  accomplished  has 
been  condensed  from  "Jour,  of  the  Franklin  Institute,"  to  which  we 
are  likewise  indebted  for  the  cuts. 
Pictet's  apparatus,  Fig.  1,  contains  two  pairs  of  pumps,  ^and  5,so 
coupled  that  while  one  exhausts  the  other  compresses.  One  pair  oper- 
ates upon  liquid  sulphurous  anhydrid  contained  in  the  annular  recipient 
C,  its  evaporation  reducing  the  temperature  to — 65°C.  ;  the  gas  is 
pumped  into  Z),  where  it  is  condensed  by  pressure  and  cold  water,  and 
returns  through  d  to  C.  The  other  pumps  remove  from  the  annular 
recipient,  Hy  liquid  carbonic  acid,  the  evaporation  reducing  the  tem- 
perature to  — 1400,  and  force  the  gas  into  Ky  where  it  is  recondensed 
by  pressure  and  cold,  the  liquid  flowing  through  k  again  into  H. 
Fig.  2. 
L  is  a  wrought-iron  retort  resisting  a  pressure  of  500  atmospheres,  in 
which  oxygen  is  generated  from  a  mixture  of  chlorate  with  chloride  of 
potassium.  When  the  pressure  in  the  tube  M  has  reached  320  atmos- 
pheres, the  temperature  of  the  contents  being  — 1400,  the  removing  of 
the  plug  A7"  opens  the  orifice  P,  through  which  the  oxygen  escapes  with 
violence,  producing  an  absorption  of  heat  sufficiently  great  that  a  part 
of  the  gas  liquefies  in  and  is  thrown  out  in  a  liquid  jet  from  the 
orifice  if  the  apparatus  be  inclined. 
The  same  retort,  tube  and  condenser  are  shown  in  Fig.  2,  in  which 
the  entrance  of  the  liquid  carbon  dioxide  is  shown  at  a,  and  the  exit  of 
the  vapors  withdrawn  by  the  suction  pump  at  b.  Instead  of  the  orifice 
in  the  tubulure  of  the  retort  the  condenser  is  closed  with  a  screw  valve, 
Ey  which  connects  with  a  manometer,  graduated  to  800  atmospheres. 
