INDUSTRIAL  APPLICATION  OF  BARYTA. 
137 
author  has  succeeded  in  retaining  a  great  portion  of  the  uncon- 
densed  vapours.  The  baryta  dissolved  by  these  acids  is  conver- 
ted into  sulphate  by  an  addition  of  sulphuric  acid,  and  the  muri- 
atic or  nitric  acids  thus  condensed  and  isolated,  are  returned 
into  the  condensing  apparatus  of  which  they  increase  the  profits. 
There  is  a  much  greater  loss  of  muriatic  acid  than  that  caused 
by  the  imperfection  of  condensing  apparatus,  namely  that  which 
necessarily  takes  place  in  the  manufacture  of  chlorine  or  of 
chloride  of  lime  which  constitutes  the  principal  use  of  muriatic 
acid.  In  this  manufacture  more  than  half  the  muriatic  acid  em- 
ployed is  lost  in  the  form  of  chloride  of  manganese.  In  prac- 
tice, from  the  impurity  of  the  oxide  of  manganese,  this  loss  rises 
to  two-thirds,  and  becomes  of  great  importance.  The  author 
calculates  the  amount  of  loss  in  France  alone  at  two  millions  of 
francs  (<£80,000).  Many  attempts  have  been  made  to  turn  the 
residues  of  the  manufacture  of  Chlorine  to  some  account ;  the 
chloride  of  manganese  has  been  applied  to  the  purification  of  gas, 
to  the  production  of  ammoniacal  salts,  to  the  purpose  of  disin- 
fection in  some  systems  of  sewerage  ;  and  lastly,  some  attempts 
have  lately  been  made,  in  the  great  manufactory  of  Mr.  Tennant 
near  Glasgow,  to  regenerate  the  oxide  of  manganese,  and  render 
it  capable  of  again  producing  chlorine,  but  all  these  applications 
are  insignificant  compared  with  the  great  quantity  of  residue 
produced. 
The  liquid  residues  of  the  manufacture  of  chlorine  have  also 
generally  formed  serious  embarrassments  in  chemical  factories, 
and  have  even  been  productive  of  danger  to  the  public  health, 
whether  they  were  allowed  to  flow  into  streams  of  water,  or 
caused  to  penetrate  into  the  soil  by  means  of  absorbing  wells. 
After  the  condensation  of  the  acids  lost  in  the  atmosphere, 
the  author  turned  his  attention  to  the  utilization  of  those  con- 
tained in  the  liquid  residues  ;  and  he  has  succeeded  in  effecting 
this  completely,  by  availing  himself  of  a  reaction  analogous  to 
that  which  permitted  Leblanc  to  endow  France  with  the  manu- 
facture of  artificial  soda.  In  Leblanc's  process  a  mixture  of 
suitable  proportions  of  sulphate  of  soda,  chalk,  and  charcoal,  is 
converted  under  the  influence  of  a  high  temperature  into  insolu- 
ble oxysulphuret  of  calcium  and  carbonate  of  soda,  which  is  ea- 
sily isolated  in  consequence  of  its  solubility. 
