A  NEW  ACID  COMPOUND  OF  SULPHUR. 
243 
In  acetic  acid  rosin  swells ;  the  others  are  not  changed.  In 
solution  of  caustic  soda  shellac  dissolves  readily  and  rosin  with 
difficulty ;  the  others  are  not  affected  by  it.  In  bisulphide  of 
carbon,  amber  and  shellac  are  insoluble ;  copal  swells ;  elemi, 
sandrach  and  mastiche  dissolve  very  slowly,  but  damraar  and 
rosin  readily. 
Oil  of  turpentine  dissolves  neither  amber  nor  shellac,  but 
dammar,  rosin,  elemi  and  sandrach ;  mastiche  is  dissolved  very 
readily. 
Boiling  linseed  oil  affects  neither  copal  nor  amber  ;  dissolves 
shellac,  elemi  and  sandrach  with  difficulty,  but  readily  dammar, 
rosin  and  mastiche. 
Benzole  does  not  dissolve  copal,  amber  and  shellac  ;  elemi 
and  sandrach  only  with  difficulty,  but  dammar,  resin  and  mas- 
tiche readily. 
Coal  naptha  affects  neither  copal,  amber  nor  shellac  ;  is  a  poor 
solvent  for  rosin,  elemi  and  sandrach,  but  a  ready  one  for  dammar 
and  mastiche. 
Concentrated  sulphuric  acid  dissolves  all  of  the  substances  and 
colors  them  at  the  same  time  dark  brown,  with  the  exception  of 
dammar,  which  assumes  a  bright  red  color. 
Nitric  acid  imparts  a  dull  yellow  color  to  elemi,  light  brown 
to  mastiche  and  sandrach,  but  scarcely  affects  the  others. 
Solution  of  ammonia  does  not  affect  amber,  shellac,  dammar 
and  elemi  ;  copal,  sandrach  and  mastiche  swell  at  first  and  then 
dissolve  ;  resin  dissolves  very  readily. 
By  means  of  these  reactions  it  will  be  no  great  difficulty  to 
test  the  purity  of  these  substances  in  commerce. — {Polyteelinisches 
Notizhlatt,  1869,  xxiv,  S.  310.) 
A  NEW  ACID  COMPOUND  OF  SULPHUR. 
(Translated  from  the  Germaa  by  Chas.  Caspari,  Jr.) 
When  metallic  zinc  is  placed  into  an  aqueous  solution  of  sul- 
phurous acid  it  gradually  disappears,  without  the  liberation  of 
any  gas ;  tlie  result  being  the  formation  of  sulphite  and  hypo- 
sulphite of  zinc.  Prof.  Schoenbein  at  first  called  attention  to 
the  fact  that  the  solution,  during  the  reaction,  temporarily  as- 
sumes a  bright  yellow  color,  and  has  the  power  of  decolorising 
indigo,  which  latter  he  considered  due  to  an  oxidising  property 
