GUT'TA  PEKCHA.  The  concrete  juice  of
the  Isonandro  Outta,  a  tree  growing  only  in
the  Malayan  Archipelago,  and  of  other  species
of  the  same  genus.  The  stem  of  the  gutta-
percha tree  grows  to  the  diameter  of  5  or  6
feet,  and  on  being  notched  yields  a  milky
juice,  which,  after  exposure  to  the  air  for  some
time,  solidifies,  forming  the  gutta  percha  of
commerce.  It  arrives  in  this  country  in  ir-
regular blocks  of  some  pounds  in  weight,
usually  containing  a  large  portion  of  inapuri-
ties  in  the  form  of  pieces  of  wood,  stones,  and
earth.  To  prepare  this  crude  product  for
manufacturing  into  useful  articles,  the  blocks
are  first  cut  into  slices,  and  then  torn  into
shreds.  These  are  softened  by  hot  water,  and
kneaded  in  a  '  masticator,'  the  stones,  earth,
and  other  impurities,  being  gradually  washed
away  by  water.  After  several  hours  the
gutta  percha  is  found  to  be  kneaded  into  a
perfectly  homogeneous  mass,  which  is  rolled
or  drawn  into  sheets,  bands,  or  tubes,  as
required.
Frop.,  Sfo.  Gutta  percha  is  a  tough,  in-
elastic substance,  becoming  soft  and  plastic  at
212°  Pahr.,  at  which  temperature  two  pieces
may  be  firmly  welded  together.  It  is  one  of
the  best  insulators  of  electricity,  is  imper-
vious to  moisture,  and  resists  the  action  of
acids  and  alkalies  to  a  great  extent.  Its  best
solvents  are  benzol,  chloroform,  bisulphuret
of  carbon,  rectified  mineral  naphtha,  and  rec-
tified oil  of  turpentine.  All  these  dissolve  it
readily.  According  to  the  analysis  of  Payen,
the  purified  gutta  percha  of  commerce  consists
of  75  to  828  of  chemically  pure  gutta  percha,
which  is  insoluble  in  ether  and  alcohol,  and  a
white  and  a  yellow  resin,  soluble  in  boiling
alcohol.
