I 
PERMANGANATE  OF  POTASSA.  389 
or  known  in  the  market  as  Saxony  Manganese,  and  contained 
71«G3  per  cent,  of  pure  binoxide,  by  Fresenius  and  Will's 
method  of  assay.  The  hydrate  of  potassa  used  was  the  com- 
mon caustic  potassa  of  commerce,  sometimes  in  sticks,  and 
sometimes  simply  fused  in  lumps. 
Take  of  Binoxide  of  Manganese,  containing  not  less  than 
70  per  cent  of  the  oxide,  and  in  fine  powder,  six  pounds,  avoir- 
dupois. 
Fused  Hydrate  of  Potassa,  four  pounds. 
Distilled  Water,  a  sufficient  quantity. 
Put  two  pounds  of  the  potassa,  and  four  fluid  ounces  of  dis- 
tilled water  into  a  shallow  cast  iron  basin  of  two  gallons  capa- 
city, and  place  this  over  a  furnace-fire  sufficiently  brisk  to 
heat  the  bottom  of  the  basin  nearly  red  hot.  When  the  potassa 
is  dissolved,  add  to  the  solution  two  pounds  of  the  binoxide 
of  manganese  and  stir  the  mixture  constantly  until  it  is  dry. 
Then  rub  it  to  powder  in  the  basin  with  an  iron  pestle,  and 
heat  it  thoroughly,  but  short  of  redness.  While  hot,  pour  upon 
it  in  a  small  stream  a  pint  of  distilled  water,  and  so  manage 
this  that  the  whole  of  the  powder  may  be  moistened  as  quickly 
as  possible.  Stir  the  mixture  thoroughly  and  constantly  until 
it  is  again  dry,  and  then  occasionally  until  it  is  again  heated 
as  before.  Then  asperse  it  again  with  a  pint  and  a  half  of 
distilled  water,  and  stir  and  heat  the  mixture  as  before.  Re- 
peat this  heating  and  aspersion  with  one  and  a  half  pints  of 
distilled  water  again  twice,  making  four  times  in  all,  and 
then  having  heated  the  mixture,  add  one  and  a  half  gallons 
of  distilled  water,  and  heat  to  brisk  ebullition  with  stirring. 
Remove  the  basin  from  the  fire,  allow  it  to  settle  during  ten 
minutes,  and  then  very  carefully  pour  off  the  clear  solution  from 
the  sediment.  Replace  the  basin  with  the  sediment  on  the  fire, 
and  having  added  one  gallon  of  distilled  water,  again  heat  to 
boiling,  remove  from  the  fire,  settle  and  decant  as  before.  Re- 
peat the  boiling  and  decantion  again  with  half  a  gallon  of  dis- 
tilled water,  and  then  throw  away  the  residue.  Stir  the  mixed 
solution  obtained,  and  allow  it  to  settle  for  half  an  hour.  Then 
return  the  clear  portion  to  the  cleaned  iron  basin  replaced  over 
the  fire,  and  evaporate  the  whole  to  about  two  or  three  pints, 
avoiding  too  much  heat  toward  the  close  of  the  evaporation. 
