TO  BLEACH  GUTTA  PERCHA. 
377 
Water,  especially  when  hot,  decomposes  but  does  not  dissolve 
it ;  a  green  matter  and  white  flakes  of  a  salt  of  protoxide  of 
copper  are  formed,  and  ammonia  is  disengaged;  by  prolonged 
boiling  sulphide  of  copper  is  formed. 
The  new  salt  is  soluble  in  ammonia,  hyposulphite  of  soda, 
and  acetic  acid.  Heated  with  potash  it  deposits  at  the  boiling 
point  a  mixture  formed  of  protoxide  and  deatoxide  of  copper. 
The  solar  rays  decompose  the  acetic  solution,  hypochlorite 
of  soda  also  destroys  it,  forming  a  white  precipitate  containing 
protoxide  of  copper  and  tetrathionic  acid. 
Nitrate  of  silver  produces  a  white  precipitate ;  the  precipi- 
tate, however,  soon  disappears  to  give  place  to  a  green  deposit 
soluble  in  ammonia,  but  easily  giving  a  deposit  of  sulphide  of 
silver.  The  deposit  contains  copper,  silver,  and  hyposulphurous 
acid.  The  author  is  of  opinion  that  iron,  zinc,  and  silver  may 
be  substituted  for  copper  ;  besides,  ferruginous  sulphate  of  cop- 
per gives  a  quadruple  salt  containing  iron. 
The  author  has  found  for  the  percentage  composition  of  this 
salt — 
Cu.A  .  .  .  27-76 
Hap  .  .  .         .         15  52 
NH3  .  .  .  .  8  52 
S  02  ....  48-19 
thence  he  deduces  the  formula— 
S.Q_CuAS,0_CuO-f(SAHaO)+2AzH^. 
According  to  him  ammonia  here  plays  only  a  passive  part, 
acting  in  the  same  way  as  water  of  crystallization. — Chemical 
News,  London,  June  4,  1864,  from  Journal  de  Fharmacie  et  de 
Chemie. 
TO  BLEACH  GUTTA  PERCHA. 
Dissolve  gutta  percha  (one  part.)  in  20  parts  of  hot  benzole, 
shake  the    soluibn  with  one-unth  part  of  freshly  calcined 
*  This  empirical  formula  mny  he  decomposed  into — 
SaO34Cu2O.a2Oj£Nab-r-SiO2CuO,SaOJiNu0+2As!H4. 
which  gives  a  quadruple  salt  differing  from  those  already  known  only  in 
containing  three  different  bases  and  one  acid. 
