256  NEW  PROCESS  FOR  REGENERATING  OXIDE  OP  MANGANESE. 
ting  chlorine  from  hydrochloric  acid,  then  back  again  to  the  state 
of  protochioride,  and  so  on  continually.  As  regards  the  rich- 
ness of  the  oxide  produced  by  the  process  above  described,  ses- 
quioxide  is  all  that  one  would  have  expected  to  obtain  by  means 
of  it,  but  it  actually  yields  a  richer  product  than  sesquioxide. 
Sesquioxide  of  manganese  is,  practically— at  least  from  a  chlorine 
manufacturer's  point  of  view— a  mixture  or  compound  of  about 
55-5  per  cent,  (being  one  equivalent)  of  binoxide  with  about 
44*5  per  cent,  (being  also  one  equivalent)  of  protoxide ;  while 
the  oxide  most  frequently  obtained  by  the  process  above  de- 
scribed contains  about  65  per  cent,  of  binoxide,  which  is  about 
the  proportion  of  binoxide  that  would  be  contained  in  a  mixture 
or  compound  of  three  equivalents  of  binoxide  with  two  equiva- 
lents of  protoxide.  The  richest  native  oxide  of  manganese 
which  chlorine  manufacturers  have  been  in  the  habit  of  using, 
contain  about  70  per  cent,  of  binoxide  ;  but  a  native  oxide  is 
practically  much  less  valuable,  so  far  as  the  manufacture  of 
chlorine  is  concerned,  than  an  artificial  oxide  containing  con- 
siderably less  oxygen.  The  reason  is,  that  in  order  to  dissolve 
a  hard,  compact,  anhydrous  native  oxide  of  manganese,  it  has  to 
be  digested  with  a  large  excess  of  acid,  resulting  in  the  produc- 
tion of  a  still-liquor  containing  a  very  large  quantity  of  free  acid, 
all  of  which  is  practically  lost;  whereas  a  recently  formed  arti- 
ficial, hydrated  oxide,  in  an  exceedingly  minute  state  of  division, 
will  dissolve  in  a  bare  equivalent  of  acid,  producing  a  still- 
liquor  containing  no  free  acid  at  all.  Hence,  whereas  when  using 
a  70  per  cent,  native  oxide,  it  is  rarely  found  possible  to  obtain 
in  the  free  state  more  than  one-sixth  of  the  chlorine  contained 
in  the  hydrochloric  acid  put  into  the  stills,  an  artificial  oxide  of 
less  even  than  60  per  cent,  will  liberate  fully  one-third  of  the 
chlorine  contained  in  the  acid  put  into  the  stills,  and  this  in  far 
less  time,  and  at  a  much  less  cost  for  labor  and  fuel,  than  the 
native  oxide  requires  for  the  liberation  of  half  the  quantity. 
The  process  which  I  have  had  the  honor  to  bring  before  the 
section,  thus,  not  only  substitutes  the  cost  of  about  seven  shil- 
lings' worth  of  lime  and  three  shillings'  worth  of  blowing  for 
every  six  or  seven  pounds  which  the  manufacturer  of  bleaching- 
powder  and  other  chlorine  products  has  hitherto  had  to  spend 
i 
