136 
INDUSTRIAL  APPLICATION  OF  BARYTA. 
liquid  contained  to  expand  in  accordance  with  the  temperature 
to  which  it  may  be  subjected,  a  very  simple  calculation  will  show 
that  the  re-establishment  of  the  equilibrium  is  independent  of 
the  temperature.  As,  moreover,  the  metal  of  which  the  instru- 
ment is  made,  is  very  thin  and  a  good  conductor  of  heat,  the 
equilibrium  of  temperature  will  soon  be  established  between  the 
interior  and  exterior  liquid. 
Now,  to  reproduce  in  any  quantity,  a  liquid  of  given  specific 
gravity ;  fill  the  areometer  with  the  given  liquid,  and  plunge  it 
and  the  equilibriating  weight  into  the  heavier  of  the  liquids  to 
be  mixed,  and  add  the  other  until  the  equilibrium  is  restored. 
The  liquids  will  be  rigorously  of  the  same  specific  gravity. — 
Journ.  Frank.  Inst,  from  Academic  des  Science  de  Paris,  June  7, 
1858. 
ON  THE  INDUSTRIAL  APPLICATION  OF  BARYTA; 
Br  F.  KUHLMANN; 
The  author  has  already  called  attention  to  the  utility  of  sul- 
phate of  baryta  in  painting,  in  distemper  and  silicious  painting, 
especially  as  the  substitution  of  this  white  compound  for  white 
lead  and  zinc  white  is  not  only  supported  by  considerations  of 
economy,  inalterability,  and  durability,  but  also  by  considerations 
of  hygiene.  This  double  advantage  has  led  the  author  to  perse- 
vere in  the  endeavor  to  produce  sulphate  of  baryta  at  a  cheap 
rate  on  a  large  scale,  and  the  present  paper  contains  the  first 
portion  of  his  results. 
To  obtain  artificial  sulphate  of  baryta  at  a  moderate  price, 
the  first  point  was  to  reduce  the  price  of  the  acids  which  consti- 
tute the  principal  expense  of  its  manufacture.  With  this  view 
the  author  has  endeavoured  to  condense  the  acid  vapors  more 
completely,  as  a  portion  of  them  is  lost  in  the  soda  manufac- 
tories to  the  great  prejudice  of  the  manufacturers,  the  public 
health,  and  vegetation. 
By  placing  native  carbonate  of  baryta  (Witherite)  in  contact 
with  the  vapors  escaping  from  the  furnaces  for  the  decomposi- 
tion of  common  salt,  or  from  our  leaden  chambers,  after  their 
condensation  has  been  effected  under  ordinary  conditions,  the 
