444 
PREPARATION  OF  VERMILLION. 
per  cent,  resist  the  action  of  aqua  regia,  and  were  not  dis- 
solved after  boiling  with  excess  of  the  latter  for  upwards  of  two 
hours. 
The  preparation  of  selenium  from  this  impure  sulphur  is  not 
difficult.  The  substance  being  finely  pulverised,  is  oxidised  by 
aqua  regia,  the  solution  diluted  and  filtered,  thus  separating  the 
sulphur  which  remains  undissolved.  A  few  crystals  of  sulphite 
of  soda  are  then  dissolved  in  the  liquid,  until  the  latter  acquires 
a  permanent  odor  of  sulphurous  acid,  and  the  whole  allowed  to 
repose  for  about  forty-eight  hours,  at  the  expiration  of  which 
the  whole  of  the  selenium  is  deposited  as  a  rose-red  powder.  In 
this  manner  from  0-3  to  0-4  per  cent,  of  selenium  can  be  ob- 
tained ;  but  if,  instead  of  using  aqua  regia  to  oxidise  the  sul- 
phur, the  latter  be  treated  with  carbonate  of  soda,  and  nitre,  in 
the  dry  way,  no  selenium  at  all  is  obtained  Chem.  News, 
London,  June  21,  1861, 
PREPARATION  OF  VERMILLION. 
By  M.  Ringaud. 
M.  Ringaud  has  patented  in  France  the  following  improve- 
ments in  preparing  this  pigment : — 
1.  Washing  with  nitric  acid  to  take  out  excess  of  sulphur  and 
oxides  of  mercury. 
2.  Washing  with  solution  of  a  mixture  of  sulphate  of  potash 
and  caustic  potash. 
3.  Digestion  of  hydrochloric  acid. 
4.  Boiling  in  solution  of  caustic  potash,  which  gives  it  a  more 
or  less  violet  tone. 
The  advantage  of  washing  with  acids  is  already  known,  but 
the  treatment  with  alkalies  is  new. 
The  vermillion  prepared  by  M.  Ringaud,  after  being  treated 
by  the  various  solutions  in  the  systematic  order  given  above,  is 
said  to  be  of  unprecedented  beauty — London  Pharm.  Journ., 
May,  1862,  from  Journ.  de  Chimie  Medicale. 
