INDUSTRIAL  APPLICATION  OF  BARYTA. 
141 
Sulphuret  of  barium  may  be  substituted  for  the  native  carbo- 
nate and  the  chloride  ;  but  the  tartrate  of  baryta  produced 
by  this  reaction  has  a  gelatinous  appearance  and  is  washed 
with  difficulty;  whilst  with  the  carbonate  and  chloride  the 
tartrate  is  granulated  and  its  washing  is  very  easy.  The  only 
advantage  that  would  be  presented  by  the  employment  of  the 
sulphuret  would  be  its  furnishing  sulphuret,  instead  of  chloride 
of  potassium,  the  former  being  the  more  valuable. 
Manufacture  of  citric  acid. 
The  same  process  is  applicable  to  this  purpose,  with  the 
same  advantages.  Lemon  juice,  concentrated  or  not,  is  con- 
verted into  citrate  of  baryta  by  means  of  pulverized  native 
carbonate,  with  the  assistance  of  heat;  the  saturation  being 
completed  by  means  of  a  little  sulphuret  of  barium,  baryta 
precipitated  by  caustic  soda,  chloride  of  barium  mixed  with  ammo- 
nia, or  even  by  ammonia  alone.  These  bodies  precipitate  the 
citrate  retained  in  solution  by  an  excess  of  citric  acid.  The 
citrate  obtained  may  be  purified  by  washing  with  cold  water. 
Its  decomposition  must  be  effected  with  the  aid  of  heat,  by  1 
equiv.  of  sulphuric  acid  of  spec.  grav.  1*831,  diluted  with  5  or 
6  parts  of  water.  To  ascertain  the  quantity  of  sulphuric  acid 
necessary  for  the  decomposition  of  the  citrate  of  baryta  (and 
also  of  the  other  barytic  salts  here  mentioned),  a  known  quantity 
should  be  incinerated  with  the  addition  of  a  little  pure  nitrate 
of  potash,  and  the  amount  of  baryta  determined. 
The  citric  acid  thus  isolated,  crystallizes  with  much  greater 
facility  than  when  citrate  of  lime  is  decomposed  by  sulphuric 
acid  ;  in  the  latter  case  the  citric  acid  retains  some  sulphate  of 
lime. 
Manufacture  of  acetic  acid. 
When  crude  pyroligneous  acid  is  saturated  with  native  carbo- 
nate of  baryta  or  sulphuret  of  barium,  it  furnishes  an  acetate 
Which  should  be  calcined  at  a  moderate  temperature,  to  avoid 
decomposing  it,  but  sufficiently  to  cause  its  solution  to  deposit 
the  tarry  matter.  In  all  cases  it  is  necessary  in  this  calcination 
to  keep  below  a  red  heat.  This  operation  may,  if  necessary,  be 
repeated  several  times. 
