542 
ON  PURE  WHITE  GUTTA  PERCHA. 
and  shows  that  the  temperature  at  the  commencement  of  the  re- 
action is  170°,  falling  as  soon  as  the  reaction  is  in  full  activity 
to  about  164°,  in  the  vicinity  of  which  it  remains  till  near  the 
close,  when,  simultaneous  with  the  stopping  of  distillation,  the 
temperature  gradually  rises  to  nearly  190°.  The  ether  obtained 
by  the  above  process  has  a  sp.  gr.  at  56°  of  -910,  and  usually 
amounts  to  very  nearly  five  fluidounces  ;  this,  diluted  as  directed, 
has  the  sp.  gr.  *887,  and  contains  the  percentage  of  ether  re- 
quired by  the  Pharmacopoeia.  It  is  as  little  affected  by  the  liquor 
potassse  test  as  the  best  samples  in  the  market ;  is  equal  to  them 
in  ever  particular,  and  can  be  prepared  at  a  less  cost  than  the 
price  asked  for  them.  The  process  is  easy  of  execution,  and 
produces  definite  results ;  the  apparatus  is  simple,  compact  and 
inexpensive,  and  not,  with  ordinary  care,  liable  to  fracture. 
With  it  the  apothecary  can  readily  prepare  a  sweet  spirit  of 
nitre  that  he  can  conscientiously  dispense,  and  not  be  dependent 
on  the  market  for  his  supply  of  this  important  remedy.  —  The 
Pharmacist,  Sept.,  1868. 
ON  PURE  WHITE  GUTTA  PERCHA. 
By  F.  Baden  Benger. 
The  demand  for  this  substance,  for  dental  purposes,  is  now 
sufficiently  established  to  justify  me  in  making  a  few  remarks  on 
it  and  its  preparation.  I  have  examined  specimens  of  the  so- 
called  "  pure  white  gutta  percha  "  now  commonly  sold,  and  find 
that  for  the  most  part  they  may  have  been  designated  almost  as 
correctly  "  pure  white  oxide  of  zinc,"  being  made  up  with  this 
substance  in  very  large  proportions,  and  I  believe  thereby  ren- 
dered less  tough,  durable  and  fit  for  the  purpose ;  this  opinion 
has  been  strengthened  by  the  fact  that  persons  to  whom  the  pure 
and  afterwards  the  commercial  article  have  been  supplied,  have 
frequently  complained  of  the  inefficiency  of  the  latter.  I  am 
further  induced  to  describe  the  process  I  use,  by  the  very  high 
price  required  by  makers  of  the  really  pure  substance. 
A  good  sample  of  crude  gutta  percha  will  yield  at  least  75  per 
cent,  of  the  pure  resin.  Some  care  should  be  taken  to  obtain  a 
specimen  with  as  little  impurity  as  possible.    The  bottle  marked 
