MANUFACTURE  OF  SULPHATE  OF  BARYTA.  451 
Dissolve  the  precipitated  extract  of  bark  in  the  wine  and  filter 
through  paper.  Dilute  the  solution  of  persulphate  of  iron  with 
a  sufficient  quantity  of  water,  (about  one  quart)  and  add  a  suffi- 
cient quantity  of  water  of  ammonia  to  precipitate  the  peroxide  ; 
wash  the  precipitate  in  the  usual  manner,  drain  it  on  a  muslin 
filter,  transfer  the  washed  magma  to  a  porcelain  dish,  and  add 
the  citric  acid  previously  reduced  to  a  fine  powder,  then  apply  a 
gentle  heat,  stirring  constantly  until  the  oxide  is  dissolved,  when 
add  three  and  a  half  drachms  of  water  of  ammonia  ;  taking  care 
that  the  latter  is  not  in  excess.  The  bright  green  solution  of 
ammonio-percitrate  of  iron  obtained,  should  be  reduced  by  gentle 
evaporation  to  four  fluid  ounces,  and  then  poured  into  the  24 
fluid-ounces  of  vinous  solution  of  precipitated  extract  of  bark, 
above  described.  Our  medical  friend  prefers,  in  some  cases,  the 
above  preparation  of  half  the  given  strength,  which  is  prepared 
by  using  wine  enough  to  make  the  whole  measure  56  instead  of 
28  fluid-ounces.  The  flavor  of  the  wine  may  be  improved  by  the 
addition  of  a  small  quantity  of  strong  tincture  of  orange  peel, 
or  a  few  drops  of  fresh  oil  of  orange  Journ*  Trans,  Md.  CoL 
Pharm.,  June,  1859. 
ON  THE  MANUFACTURE  OF  SULPHATE  OF  BARYTA. 
By  J.  Pelouze. 
Several  manufacturers  of  chemicals  prepare  sulphate  of  bary- 
ta, known  by  the  name  of  "  baryta-white,"  by  treating  native  car- 
bonate of  baryta  with  hydrochloric  acid,  and  precipitating  the 
solution  obtained  by  sulphuric  acid  ;  thus  regenerating  the  hy- 
drochloric acid  which  may  be  used  for  further  operations. 
This  sulphate,  in  spite  of  its  being  dearer  than  that  which  is 
prepared  by  other  less  costly  processes,  is  always  preferred  to 
the  latter  for  painting. 
I  have  discovered  that  a  sulphate  of  baryta,  similar  to  that 
now  in  question,  can  be  obtained  by  treating  directly  carbonate 
of  baryta  with  dilute  sulphuric  acid,  without  its  being  necessary 
to  pulverize  the  former.  A  very  small  quantity  of  hydrochloric 
acid,  3  to  4  hundredths  for  example,  is  added  to  the  diluted 
sulphuric  acid,  and  the  whole  kept  at  a  slight  ebullition.  The 
