INDUSTRIAL  APPLICATION  OF  BARYTA. 
139 
The  product  of  this  lixiviation  consists  of  a  perfectly  clear  so- 
lution of  nearly  pure  chloride  of  barium.  If  there  be  a  slight  ex- 
cess of  sulphuret  of  barium,  giving  it  a  yellowish  color,  this  is  re- 
moved by  the  addition,  until  complete  decolorization,  of  a  solu- 
tion of  chloride  of  manganese,  the  residue  of  the  manufacture  of 
chlorine,  from  which  all  the  chloride  of  iron  has  been  separated 
by  a  previous  digestion  with  native  carbonate  of  baryta.  If,  on 
the  contrary,  there  is  a  slight  excess  of  the  salt  of  manganese,  ic 
is  got  rid  of  by  a  little  sulphuret  of  barium. 
A  circumstance  of  some  interest,  especially  in  a  scientific  point 
of  view,  is  that  in  clearing  out  a  furnace,  the  author  found  that 
in  the  part  of  this  furnace  where  the  sulphate  of  baryta  was  near- 
est to  the  grate,  and  where  at  the  same  time  it  was  in  contact 
with  the  brick,  there  was  an  abundant  deposit  of  a  green  and 
blue  matter,  containing  no  soda,  manganese  or  cobalt,  and  which 
appeared  to  be  an  ultramarine  in  which  baryta  replaced  the  soda. 
The  author  calls  attention  to  the  fact,  that  before  the  Societe  d* 
Encouragement  proposed  a  prize  for  the  discovery  of  a  means  of 
manufacturing  artificial  ultramine,  M.  Tassart  had  indicated  the 
production,  in  a  soda  furnace,  of  a  blue  matter  which  M.  Vau- 
quelin  recognized  as  ultramine,  and  that  soon  after  this  first  ob- 
servation he  noticed  the  production  of  the  same  artificial  ultra- 
marine, under  circumstances  which  rendered  the  explanation  of 
the  phenomena  of  its  formation  less  difficult,  in  a  portion  of  the 
furnaces  for  the  calcination  of  sulphate  of  soda,  where  this  sul- 
phate was  in  contact  with  the  bricks  at  a  high  temperature. 
The  first  observation  of  the  existence  of  a  barytic  ultramarine, 
under  analogous  circumstances,  would  furnish  another  proof  that 
the  germ  of  a  discovery  may  lie  in  an  attentive  examination  of 
some  fragments  of  a  furnace  in  course  of  demolition. 
Manufacture  of  various  acids. 
In  his  previous  memoir  the  author  indicated  the  uses  to  which 
he  has  put  the  chloride  of  barium  which  constitutes  the  base  of 
his  operations.  He  stated  particularly  that  by  mixing  a  con- 
centrated hot  solution  of  chloride  of  barium  with  a  solution  of 
caustic  soda,  hydrated  baryta  was  obtained,  and  that  anhydrous 
baryta  might  be  economically  procured  by  the  calculation  of 
nitrate  of  baryta  prepared  from  the  chloride.  The  nitrate 
decomposed  by  sulphuric  acid  served  for  the  manufacture  of  ni- 
tric acid  without  distillation,  and  of  artificial  sulphate  of  baryta, 
