608 
Chemical  Notes. 
f  Am.  Jour.  Pharm. 
I      Dec,  1881. 
native  strontianite — that  is  90  to  95  per  cent,  pure  carbonate  of 
strontia — has  not  been  worked  systematically  in  mines;  but  what 
used  to  be  brought  to  the  market  was  an  inferior  stone  collected  in 
various  parts  of  Germany,  chiefly  in  Westphalia,  where  it  is  found  on 
the  surface  of  the  fields.  Stimulated  by  the  demand  likely  to  arise 
for  it  in  consequence  of  Dr.  Scheibler's  discovery,  new  localities  have 
been  opened  up  and  deposits  of  considerable  importance  have  been 
found  in  Westphalia  at  great  depths.  A  supply  of  over  ten  thous- 
and tons  per  annum  seems  to  be  assured,  whereas  only  a  short  time 
ago  it  was  not  thought  possible  that  more  than  a  few  hundred  tons- 
could  in  all  be  provided. — Chem.  News,  Oct.  21,  1881,  p.  205. 
On  the  Composition  of  Bleaching  Powder. — Professor  Lunge,  of 
Zurich,  jointly  with  H.  Schseffe,  has  given  the  question  of  the  exact 
composition  of  bleaching  powder  a  thorough  study,  and  reaches  the 
following  results : 
1.  The  most  probable  formula  for  bleaching-powder  is  that  pro- 
f  CI 
posed  by  Odling,  Ca  <  qqy   Bleaching-powder  dried  over  sulphuric 
acid  contains  the  hydrate,  2CaOCl2+H20.  Any  percentage  of  calcium 
in  bleaching-powder  over  and  above  tliat  demaiided  by  this  formula 
is  from  free  calcium  hydrate,  which  being  mechanically  enclosed  by 
the  bleaching-powder  already  formed  is  withdrawn  from  the  action  of 
the  chlorine,  so  that,  even  in  experiments  on  a  small  scale,  instead  of 
the  theoretical  47  per  cent,  (allowing  for  the  9  to  10  per  cent,  of 
hygroscopic  moisture  found  by  analysis)  only  43' 5  per  cent,  is  gotten. 
2.  The  flocculent  residue  left  when  bleaching-powder  is  dissolved  in 
water  is  for  the  most  part  calcium  hydrate,  but  contains  a  little  of  a. 
bleaching  compound  only  slowly  decomposed  by  water. 
3.  Strong  mineral  acids,  if  not  used  in  excess,  will  develop  from 
bleaching-powder  solutions  only  hypochlorous  acid  ;  carbonic  acid  has- 
the  same  effect. 
4.  Dry  carbonic  acid  gas,  with  the  aid  of  gentle  heat,  will  drive  almost 
all  the  chlorine  out  of  solid  bleaching-powder. 
5.  Moist  air  and  heat  will  develop  oxygen  only  from  bleaching- 
powder  ;  dry  air,  however,  will  liberate  chlorine  also. 
6.  The  next  favorable  condition  for  the  formation  of  a  strong 
bleaching-powder  is  the  presence  of  4  per  cent,  of  water  over  and 
above  that  needed  for  the  formation  of  the  calcium  hydrate  (using- 
dry  chlorine)  and  a  temperature  of  20°  to  60 °C.     The  strongest 
