62  FATTY  ACIDS  FOR  THE  MANUFACTURE  OF  CANDLES. 
be  introduced  into  the  gas  apparatus,  the  spots  on  the  porcelain  at 
first  contain  principally  only  arsenic,  apparently  in  consequence  of 
the  antimony  being  less  volatile  ;  but  if  shining  spots  be  produced 
on  the  porcelain,  which  contain  more  antimony,  these  resist  the 
action  of  hypochlorite  of  soda  in  a  greater  or  less  degree,  and  are 
often  only  eaten  away  round  the  edges. 
Small  quantities  of  antimony  in  the  arsenical  spots  render  these 
strong  and  more  shining,  but  do  not  prevent  their  solution  in  hypo- 
chlorite of  soda.  The  hypochlorite  of  soda  may  therefore  be  used 
with  the  greatest  certainty  in  distinguishing  purely  arsenical  from 
purely  antimonial  spots,  which  indeed  is  the  principal  point  in  ju- 
dicial investigations,  but  not  in  detecting  a  trace  of  antimony  in 
arsenical  spots;  it  also  serves  in  some  measure  to  detect  traces  of 
arsenic  in  antimonial  spots.  It  might  be  possible,  but  probably 
useless  in  practice,  to  ascertain  by  comparative  investigations  the 
quantitative  proportions  of  arsenic  and  antimony  at  which  distinct 
differences  occur  in  the  behaviour  of  mixed  metallic  spots  with  hy- 
pochlorite of  soda. — Chemical  Gazette,  Aug*  2,  1852,  from  Ar- 
chiv  der  Pharm.,  lxx.  p.  14. 
PREPARATION  OF  PURE  FATTY  ACIDS  FOR  THE  MANUFACTURE 
OF  CANDLES  BY  THE  DISTILLATION  OF  COMMON  FATS. 
At  the  last  Conversazion,  held  at  the  house  of  the  Pharmaceu- 
tical Society,  a  series  of  specimens  were  exhibited  illustrating  the 
process  adopted  at  the  works  of  Price's  Patent  Candle  Company 
for  obtaining  a  white  and  hard  fatty  substance,  suitable  for  the 
manufacture  of  the  best  description  of  candles,  by  distillation  from 
palm  oil  and  other  cheap  fats.  The  following  description  of  the 
details  of  the  process  is  given  in  the  "Reports  of  the  Juries"  of 
the  Great  Exhibition. 
Sulphuric  Saponification. — About  twenty  tons  of  fat,  say  palm 
oil,  are  placed  in  a  large  lead-lined  vat,  and  fused  by  a  steam  jet. 
The  fluid  mass,  alter  being  allowed  to  settle,  has  now  to  be  exposed 
to  the  combined  action  of  concentrated  sulphuric  acid  and  heat, 
and  for  this  purpose  is  pumped  up  into  the  acidifying  vessel,  in 
which  its  temperature  is  raised  to  177°  Cent.  (350°  Far.).  The 
means  of  heating  is  a  jet  of  low-pressure  steam,  which,  in  its  course 
v 
