524 
BLEACHING  OF  WAX,  ETC. 
and  deposits  in  the  upper  pan.  It  is  allowed  to  repose  in  this 
for  about  four  or  five  minutes  after  each  passage ;  and  after  the 
last  one,  about  one  or  two  hours,  according  to  quantity,  in  order 
to  allow  of  any  impurities  to  subside.  The  wax  is  then  granu- 
lated in  the  ordinary  way  by  means  of  cold  water,  is  allowed  to 
dry  during  two  or  three  days,  and  the  action  of  light  and  air 
does  the  rest,  for  which  one  person  is  sufficient.  The  whole  of 
the  operations  do  not  require  more  than  a  few  days,  are  perfectly 
certain,  and  are  attended  with- no  danger.  Independent  of  the 
advantage  which  such  an  apparatus  has  for  bleaching  wax,  it  has 
also  that  of  enabling  its  qualities,  according  to  relative  whiteness, 
to  be  distinguished ;  for  this  purpose  it  is  necessary  to  present 
the  wax  in  mass  to  the  end  of  the  worm,  and  in  a  second  or  two 
the  vapor  determines  the  relative  color  which  it  will  yield. 
This  process  is  also  applicable  to  the  purification  of  tallows  and 
of  oils;  even  fish- oil,  when  passed  through  the  apparatus  of  M. 
Cassgrand,  and  washed  as  just  described,  is  completely  deprived 
of  its  disagreeable  smell ;  and  if  it  be  set  aside  in  a  place  where 
the  temperature  only  reaches  from  59°  to  68°  F.,  a  fresh  deposit 
will  form,  and  the  oil  will  become  perfectly  clarified  and  nearly 
colorless. 
This  process  has  considerable  analogy  with  one  which  Mr. 
Dixon,  of  Dublin,  patented  some  time  since  for  bleaching  palm- 
oil,  the  principle  of  which  was  exposing  the  oil  to  the  action  of 
steam.  Cassgrand's  apparatus  might,  no  doubt,  be  applied  to 
the  same  purpose,  and  appear^  to  us  to  have  certain  advantages 
over  that  of  Dixon,  especially  in  exposing  a  larger  surface  to  the 
action  of  the  steam,  and  varying  that  surface  oftener.  If  not 
already  known  here,  the  process  is  worthy  of  the  serious  atten- 
tion of  soap-boilers.  Such  a  method  would  evidently  be  much 
more  effective  than  the  present  system  of  purifying  oils,  especially 
where  sulphuric  acid  is  used,  which  is  almost  universally  the  case. 
As  that  acid  is  scarcely  ever  effectively  removed,  many  samples 
of  trotter,  rape  and  other  similar  oils,  are  usually  quite  acid ; 
where  the  former  is  used  for  the  manufacture  of  hair-oil,  it  is  very 
destructive  to  the  hair,  and  the  latter  destroys  the  lamps  when 
used  for  burning,  &c.  The  only  modification  required  for  the 
purification  of  oil  would  be  to  divide  the  oil  as  much  as  possible 
by  means  of  a  diaphragm  of  copper,  pierced  with  holes,  in  the 
