MANUFACTURE  OF  CHLORINE,  ETC.  541 
of  manganese  which  is  treated  with  air  in  the  wet  way  has  lime 
associated  with  it,  the  Mn02  which  forms  (or  part  of  it,  accor- 
ding to  the  proportion  of  Jime  present)  combines  with  CaO  instead 
of  with  MnO,  thus  leaving  free  to  undergo  peroxidation  that 
part  of  the  MnO  which,  but  for  the  presence  of  the  CaO,  this 
MnOg  must  have  been  combined  with,  and  which  would  thus  have 
got  locked  up  in  a  state  in  which  it  would  have  been  incapable 
of  being  peroxidised,  at  least  in  the  wet  way  and  by  air  alone. 
Hence,  the  presence  of  enough  lime  to  take  the  place  of  that 
half  of  the  protoxide  which,  if  no  lime  were  present,  would  have 
to  go  into  combination  as  base,  and  also  to  supply  enough 
base  for  that  half  itself  to  combine  with  after  undergoing 
peroxidation,  will  enable  the  whole  of  the  MnO  operated  upon 
to  be  raised  to  the  state  of  MnOg.  The  minimum  quantity  of 
lime  which  is  enough  for  this  purpose  is  an  equivalent  for  each 
equivalent  of  MnO  operated  upon,  or  the  quantity  necessary  to 
supply  an  equivalent  of  lime  to  all  the  Mn02  which  can  be  pro- 
duced by  the  peroxidation  of  all  the  MnO. 
By  treating  with  air,  then,  a  mixture  of  protoxide  of  man- 
ganese and  lime  suspended  either  in  water  or  in  solution  of 
chloride  of  calcium,  there  is  formed  a  compound  containing 
Mn02  and  CaO,  in  the  proportion  of  an  equivalent  of  one  to  an 
equivalent  of  the  other.  This  compound  may  be  regarded  as 
sesquioxide  of  manganese,  or  Mn203,  the  MnO  in  which  is  re- 
placed by  CaO.  I  call  it  manganite  of  calcium,  and  I  believe 
it  to  be  a  new  compound.  Gorgrew,  in  1852,  described  a  com- 
pound which  he  called  manganite  of  calcium  ;  but  his  compound 
contained  five  equivalents  of  MnOg  per  equivalent  of  CaO,  and 
the  CaO  in  it  was  so  feebly  combined  that  it  readily  decom- 
posed chloride  of  manganese.  My  compound  contains  only  one 
equivalent  of  Mn02  per  equivalent  of  CaO,  and  has  no  action 
upon  salts  of  manganese. 
This  compound  has  now  been  produced  and  re-produced  to  the 
extent  of  some  hundreds  of  tons.  The  process  of  producing  it 
and  applying  it  to  the  manufacture  of  chlorine  is  conducted  as 
follows  : — The  residual  liquor  which  remains  after  a  charge  of 
manganite  has  reacted  upon  hydrochloric  acid  in  any  suitable 
still  is  run  from  the  still  into  a  well  or  other  receptacle,  in  which 
