80       PERMANGANATE  OF  POTASH  AS  AN  OXIDIZING  AGENT. 
iierence  to  the  precipitate  of  sulphate  of  baryta.  The  lat- 
ter is  then  washed  with  distilled  water  on  the  filter  until  the 
washing-water  produces  no  turbidity  in  nitrate  of  silver.  The 
filter  is  calcined  with  its  contents  in  a  platinum  capsule,  and 
weighed,  deducting  the  weight  of  the  ashes  of  the  filter  in  the 
ordinary  way. 
In  a  laboratory  where  numerous  determinations  of  sulphur 
have  to  be  made  daily,  instead  of  collecting  and  weighing  the 
sulphate  of  baryta,  the  liquid  might  be  precipitated  by  a  nor- 
mal solution  of  chloride  of  barium  by  the  method  of  successive 
approximations.  The  results  are  very  exact,  and  the  whole 
operation  does  not  last  more  than  a  quarter  of  an  hour. 
The  finely  divided  carbon  contained  in  powder  being  readily 
and  completely  oxidized  by  permanganate  of  potash,  the  authors 
think  it  possible  that  this  reagent  may  be  applied  to  the  deter- 
mination of  the  carbon  contained  in  animal  charcoal,  or  in  other 
matters  containing  finely  divided  carbon. 
The  analysis  of  the  saline  compounds  of  sulphur  is  very  easi- 
ly effected  by  permanganate  of  potash.  Hyposulphite  of  soda 
reduces  the  solution  of  permanganate  immediately  in  the  cold, 
and  by  adopting  the  same  course  as  with  gunpowder,  the  authors 
obtained  the  following  results : — 1-000  gr.  of  commercial  crys- 
tallized hyposulphite  of  soda  gave  1-850  gr.  of  sulphate  of 
baryta,  containing  0-254  gr.  of  sulphur.  Calculation  from  the 
formula  S202,  NaO,  5HO  requires  0-258  gr. 
The  authors  have  ascertained  that  this  method  does  not  apply 
only  to  bodies  which  attract  oxygen  with  avidity,  but  that  the 
most  stable  sulphuretted  compounds  are  completely  oxidized  by 
permanganate  of  potash,  the  sulphur  being  entirely  converted 
into  sulphuric  acid  ;  thus  sulphuret  of  carbon,  which  resists  ebul- 
lition with  fuming  nitric  acid,  and  dissolves  hyponitric  acid  with- 
out being  decomposed,  becomes  completely  changed  into  sul- 
phate of  potash  and  carbonic  acid  when  boiled  with  a  solution 
of  permanganate  of  potash. 
Different  organic  sulphuretted  compounds,  especially  hydro- 
sulphate  of  sulphuret  of  benzyole,  behave  in  the  same  way.  The 
authors  therefore  hope  that  this  method  will  advantageously  re- 
place the  oxidation  of  sulphuretted  matters  by  the  mixture  cf 
