244 
A  NEW  ACID  COMPOUND  OF  SULPHUR. 
of  the  liquid,  and  accounted  for  it  by  a  temporary  formation  of 
ozone. 
Recently,  Schutzenberger  investigated  the  matter  more  tho- 
roughly, and  July  19th,  1869,  reported  the  result  of  his  re- 
searches, contradicting  Schoenbein's  theory,  to  the  Paris 
Academy  of  Science.  He  found  that  this  discoloration  of  in- 
digo is  by  no  means  due  to  an  oxydation,  it  being  well  known 
that  indigo  is  also  discolored  and  changed  to  white  indigo  by 
powerful  reducing  agents,  regaining  its  blue  color  upon  exposure 
to  the  oxygen  of  the  atmosphere.  As  indigo,  discolored  by  the 
above  solution,  will  also  regain  its  blue  color  upon  exposure  to 
air,  it  is  evident  that  the  discoloration  is  due  to  a  reduction  of 
the  indigo,  and  this  effect,  together  with  the  yellow  tint  in  the 
solution,  must  be  owing  to  the  presence  of  a  powerful  reducing 
compound.  Its  affinity  for  oxygen  is  so  great  that  the  zinc  fil- 
ings, still  moist  with  the  solution,  upon  exposure  to  air  will  be- 
come heated  to  a  temperature  of  55 — 60°  Cent. ;  hence  its  power 
of  reducing  must  be  very  great  and  similar  to  that  of  nascent 
hydrogen.  Salts  of  copper,  silver,  mercury  and  lead  are  readily 
reduced  by  it  to  the  metallic  state,  and  bichromate  of  potassa 
to  oxide  of  chrome ;  the  salt  of  copper  deposits,  besides  the  me- 
tallic copper,  also  its  combination  with  hydrogen  (cuprous  hy- 
dride.) 
After  many  attempts,  Schutzenberger  at  last  succeeded  in 
isolating  this  new  body  and  examined  it  more  definitely ;  he 
found  it  to  be  an  acid,  very  unstable  in  its  uncombined  state, 
and  succeeded  in  isolating  it  only  by  using  an  alkaline  sulphite 
in  place  of  free  sulphurous  acid,  by  which  means  he  obtained 
the  corresponding  salt  of  the  new  acid.  By  allowing  zinc  to  act 
upon  a  concentrated  solution  of  bisulphite  of  soda,  he  obtained 
the  soda  salt  of  the  new  acid,  possessing  the  same  affinity  for 
oxygen  as  the  free  acid,  and  which  can  only  be  kept  out  of  con- 
tact with  air  ;  the  acid  is  monobasic  and  its  formula  is  HSgOg. 
The  radical  of  the  acid  contains  besides  oxygen  also  hydrogen, 
and  this  accounts  for  its  great  deoxidising  property ;  it  gives  up 
the  hydrogen  of  its  radical,  thus  liberating  nascent  hydrogen. 
S.  names  this  acid  hydrosulphurous  acid  (acide  hydrosulfureux), 
it  being  derived  from  hydrogen  and  sulphurous  acid. — (Poly- 
^echnisches  Notizblatt,  1869,  xxiv,  S.  365.) 
