AmDecuriS9arm'}    Some  Sodium  and  Manganese  Compounds,  617 
physikal.  Chem.,  ii,  390-404)  by  the  ordinary  methods,  but  the  results 
are  not  comparable,  as  Scheffer  experimented  at  lower  temperatures ; 
the  coefficients  found  for  the  other  substances  agree  better,  and  in 
some  cases  very  well.  The  diffusion  coefficients  found  for  the  three 
acids  named  above,  and  those  of  potash  and  soda,  are  in  the  same 
ratio  as  the  molecular  conductivities  of  these  electrolytes  as  deter- 
mined by  Kohlrausch  ;  but  the  coefficients  of  oxalic  acid,  acetic  acid, 
and  ammonia  are  larger  than  they  should  be  if  they  followed  the 
same  rule.  The  diffusion  coefficients,  and  those  values  which  nre 
termed  the  coefficients  of  chemical  affinity,  also  stand  in  a  direct  rela- 
tion to  one  another. 
ON  SOME  SODIUM  AND  MANGANESE  COMPOUNDS.1 
MANUFACTURE  OF  SODIUM  SULPHIDE. 
Sodium  sulphide  is  generally  made  either  by  double  decomposition 
or  by  redaction  of  sodium  sulphate.  The  former  process  was  described 
by  W.  Weldon.  Another  process  of  double  decomposition  is  that  of 
barium  sulphide  and  sodium  sulphate,  but  this  process  is  only  prac- 
ticable where  there  is  a  ready  sale  for  barium  sulphate  as  "blanc 
fixe."  As  regards  the  reduction  of  sodium  sulphate,  this  article  is 
ground  to  a  coarse  powder,  mixed  with  coal-dust  in  the  proportion  of 
3  to  2,  and  the  mixture  heated  in  a  reverbatory  furnace.  The  furnace 
is  6  meters  long,  2  meters  wide,  1*7  meters  high,  and  well  lined  with 
fire-brick.  The  bed  is  divided  into  two  portions,  that  next  to  the 
fire-bridge  for  the  reduction,  and  the  other  for  the  preliminary  heat- 
ing of  the  charge,  which  may  consist  of  VbO  kilos,  of  sodium  sulphate 
and  100  kilos,  of  coal.  About  If  hours  are  required  for  the  reduc- 
tion of  this  charge.  At  the  end  of  the  operation  the  fluxed  mass  is 
run  into  iron  boxes  which  are  well  closed,  in  order  to  prevent  oxida- 
tion. Perhaps  a  revolving  furnace  may  yet  be  employed  for  the 
reduction,  although  a  few  experiments  in  this  direction  gave  unsatis- 
factory results.  The  mass  obtained  from  the  furnace  weighs  about 
110  to  115  kilos.,  and  contains  up  to  60  per  cent,  of  sodium  sulphide. 
Its  appearance  should  be  red  and  porous,  but  not  gray  and  dense. 
The  cooled  mass  is  broken  up  into  large  balls,  and  thrown  into  lixi- 
viating vats,  arranged  and  fitted  on  the  same  principle  as  black-ash 
vats.  The  lixiviation  is  performed  with  warm  water,  and  the  liquor 
running  from  the  strongest  vat  stands  at  32°  B.    It  is  allowed  to 
1  Jour.  Soc.  Chem.  Ind.;  Oil,  Paint  and  Drug  Reporter. 
