234 
Chemical  Notes. 
(  Am.  Jour.  Piiarm. 
\      May,  1881. 
potassium.  His  results  agree  with  those  previously  obtained  by 
Lunge,  who  found  that  a  complete  change  was  only  reached  when  the 
liberated  alkali  was  neutralized  by  an  acid.  The  change  succeeds 
perfectly  in  the  cold  when  the  solution  of  ferrocyanide  is  treated  with 
lead  peroxide,  and  then  a  slight  excess  of  dilute  hydrochloric  acid 
added  with  constant  stirring.  When  red  lead  is  used  higher  tempera- 
tures and  larger  excess  of  acid  are  necessary. 
The  change  to  ferricyanide  can  also  be  effected  by  the  aid  of  man- 
ganese dioxide,  even  in  the  cold  if  to  1  molecule  of  ferrocyanide  of 
potassium  1  of  the  manganese  dioxide  is  used.  In  both  cases  there  is 
obtained  from  the  filtrate,  after  neutralizing  with  soda,  a  very  pure 
salt,  although  in  the  second  case  the  liquid  is  difficult  to  filter.  The 
author  believes  that  by  the  addition  of  carbonates  and  by  the  blowing- 
in  of  a  current  of  air,  the  manganese  sesquioxide  precipitate  can  be 
oxidized  so  that  it  will  give  no  trouble  in  washing.  Upon  adding  a 
base,  this  manganese  precipitate  is  readily  converted  into  dioxide  again. 
Either  of  the  above-mentioned  methods  seems  adapted  to  replace  the 
old  chlorine  method. — Dingier  s  Polytech.  Jour.y  238,  p.  484. 
Composition  of  Common  Hyposidpliite  of  Sodium. — A.  Bernthsen  has 
made  some  careful  experiments  with  a  view  of  determining  exactly  the 
formula  of  the  so-called  hyposulphite  (hydrosulpkite)  of  sodium. 
Taking  the  crude  solution  resulting  from  the  action  of  zinc  upon  acicl 
sulphite  of  sodium,  and  adding  chloride  of  barium  (baryta  water  was 
first  tried,  but  vitiated  results  because  of  the  formation  of  hydrogen 
sulphide)  to  remove  the  sulphurous  and  sulphuric  acids,  a  solution  was 
gotten  in  which  only  the  chloride  and  hyposulphite  of  sodium,  barium 
and  zinc  remained.  The  hyposulphite  in  dilute  solution  was  now 
treated  with  iodine,  which  changed  it  into  sulphate,  and  the  amount  of 
this  was  determined  by  the  aid  of  barium  chloride.  It  was  found  in 
this  way  that  1  atom  of  sulphur  as  hyposulphite  required  3  atoms  of 
iodine  to  convert  it  into  sulphuric  acid.  The  anhydride  of  the  hypo- 
sulphurous  acid  would  therefore  have  the  formula  S2O3. 
The  same  result  was  gotten  in  still  another  way.  The  amount  of 
ammoniacal  copper  sulphate  solution  needed  to  change  the  hyposul- 
phite into  sulphite  showed  that  for  every  2  atoms  of  sulphur  in  the 
hyposulphite  2  molecules  of  copper  sulphate  (that  is  1  atom  of  oxygen) 
were  needed  for  the  reaction  8203+0=2802- 
The  simplest  formula  for  the  sodium  salt  based  upon  this  anhydride 
is  802Na.    Bernthsen  is  inclined  to  think,  however,  that  the  double  of 
