174 
ON  THE  PREPARATION  OF  MANGANESE. 
chloride  of  barium.  This  is  necessary,  as  otherwise  in  the 
reduction  the  metal  might  contain  a  small  amount  of  sulphur. 
The  solution  filtered  from  the  precipitate  of  baryta  is  then  evapo- 
rated to  dryness,  and  the  pale  rose-colored  salt  thus  obtained  is 
fused  in  a  crucible  ;  this  takes  place  at  about  the  melting-point 
of  chloride  of  calcium.  Too  strong  a  heat  must  be  avoided,  as 
otherwise  a  portion  is  volatilized,  or  perhaps  partially  decom- 
posed. 
The  fused  saline  mass  is  poured  out  upon  a  plate  of  stone  or 
metal,  and  immediately  after  cooling  pounded  into  a  coarse 
powder  and  preserved  in  well-stoppered  bottles,  as  it  attracts 
moisture  very  readily. 
To  reduce  the  metal,  the  protochloride  of  manganese  thus  pre- 
pared is  mixed  with  an  equal  weight  of  pounded  fluor-spar  by 
agitation  in  a  flask,  and  divided  into  portions  of  about  15  grms. 
each  placed  in  a  small  corked  bottle.  Into  each  bottle  about  3 
grms.  of  sodium  freed  from  adherent  naphtha  is  put,  in  fragments 
of  the  size  of  a  pea. 
A  Hessian  crucible  is  then  heated  to  a  slight  red  heat,  and  the 
contents  of  the  bottles  are  thrown  into  it  one  by  one.  After  each 
addition  the  crucible  is  lightly  covered,  and  the  ne*xt  portion  is 
not  thrown  in  until  the  reduction,  which  takes  place  with  noise 
and  flame,  is  completed. 
When  a  crucible  capable  of  containing  4  ounces  of  water  is 
employed,  and  10  to  12  portions  have  been  thrown  into  it,  the 
mass  is  covered  for  more  certainty  with  about  1  ounce  of  fused 
and  coarsely  pounded  chloride  of  sodium.  The  fire  is  then 
strengthened  by  blowing  so  as  to  give  a  moderate  white  heat,  that 
is  to  say  about  the  temperature  required  for  the  fusion  of  cast 
iron.    This  is  continued  for  10  minutes. 
The  crucible  is  then  allowed  to  cool  slowly,  and  on  breaking 
it  the  metal  is  found  at  the  bottom  of  the  crucible,  beneath  the 
slag,  in  the  form  of  a  perfectly  fused,  roundish  regulus. 
Although  the  author  has  effected  all  his  reductions  with  the 
quantities  above  described,  there  is  no  doubt  that  the  same  pro- 
cess may  also  be  employed  on  a  larger  scale. 
The  quantity  of  metal  obtained  is  indeed  not  what  might  be 
expected  from  calculation,  nor  is  it  always  the  same.  In  such 
operations  it  is,  of  course,  impossible  to  prevent  a  considerable 
