268  Crystallization  of  Camphor.         { ^^J-^^'^^;;  f^^^f 
the  air  under  sheds,  are  then  placed  in  cast  iron  cylinders,  heated 
externally  by  steam,  and  disposed  in  such  a  way  that  a  pressure  of  air 
can  be  given  at  will,  thus  increasing  the  flow  of  oil  passing  through 
the  mixture.  The  heavy  tar  oil  heated  at  a  temperature  of  130°  C, 
by  a  steam  worm  passing  through  it,  is  allowed  to  pass  from  top  to 
bottom  over  the  mixture  to  be  treated ;  the  dissolving  liquid  collects 
in  crystallizing  vats,  where,  by  cooling,  the  sulphur  precipitates  in 
crystals;  this  same  oil  is  then,  by  a  screw  system,  raised  again  into 
the  heater,  and  allowed  to  pass  over. and  over  again  by  the  same  series 
of  operations  on  the  mixture,  until  all  the  sulphur  is  exhausted.  The 
old  purifying  mixture  retains  a  certain  amount  of  the- extractive  oil, 
of  which  it  is  deprived  by  forcing  through  it  a  current  of  steam  ;  thus 
obtaining  nearly  the  whole  amount  of  oil  used. 
The  crude  sulphur  thus  obtained  is  in  octahedric  crystals,  colored 
black  by  a  small  amount  of  tarry  substances.  Purified  by  distillation, 
it  possesses  all  the  properties  of  pure  sulphur. 
In  Europe  and  in  this  country,  an  immense  amount  of  sulphur  is 
lost  with  the  mixtures  which  have  been  used  in  purifying  gas.  Though 
sulphur  is  comparatively  low  in  price,  experiments  made  on  a  large 
scale  have  proved  that  its  extraction  is  profitable  to  the  gas  manufac- 
turer, as  the  extractive  matter  and  the  matter  from  which  the  sulphur 
is  to  be  extracted  cost  him  nothing.  From,  experiments  I  have  per- 
sonally made,  I  have  found  better  results  from  an  oil  not  possessing 
too  high  a  gravity.  The  oil  I  have  used  with  the  best  advantage 
weighed  0*995  grammes,  and  boiling  at  from  180°  to  210°  C.  I  have 
also  found  that  it  is  necessary  to  operate  at  the  temperature  of  150° 
C,  for  fear  the  sulphur  might  decompose  the  oil,  and  produce  sulpha- 
retted  hydrogen. — Journ.  of  Applied  Chem.^  Aprils  1871. 
THE  CRYSTALLIZATION  OF  CAiMPHOR. 
By  R.  Rother. 
The  peculiar  predilection  of  camphor  for  the  crystalline  form,  is 
one  of  the  petty  annoyances  inherent  to  the  dispensing  department. 
Insignificant  as  the  objection  may  seem,  it  is  nevertheless  one  for 
which  the  dispensing  pharmaceutist  is  but  too  willing  to  accept  a 
remedy.  This  difficulty  is  chiefly  experienced  with  powdered  cam- 
phor, but  the  objection,  likewise,  though  in  a  less  obvious  degree,  ap- 
plies to  the  aqueous  solution.    The  most  perfect  means  of  pulverizing 
