454  Contributions  from  the  School  of  Pharmacy^  {"^'"'oa.'isTs.''™' 
slowing  of  the  pulse,  profuse  salivation,  and,  finally,  convulsions. 
The  character  of  the  convulsions  is  very  peculiar  and  very  constant."* 
CONTRIBUTIONS  FROM   THE  SCHOOL  OF  PHARMACY  OF  THE 
UNIVERSITY  OF  MICHIGAN. 
REPORTED   BY  PROF.   ALBERT  B.  PRESCOTT. 
I.  Purification  of  Commercial  Gutta-Percha,  and  Prepara- 
tion OF  Liquor  Gutta-Percha.  By  Geo.  E.  Willmarth^ 
P.  C. 
The  preparation  of  the  solution  from  commercial  gutta  percha,  by 
clarification  with  carbonate  of  lead,  as  the  U.  S.  Pharmacopoeia  directs, 
often  gives  unsatisfactory  results.  The  carbonate  requires  a  long  time 
to  settle  and  sometimes  fails  at  last  to  separate  completely,  so  that  the 
solution,  if  colorless,  is  not  clear  and  may  be  contaminated  with  lead. 
The  methods  of  purification  tried  in  this  investigation  depend  upon 
the  principle  that  gutta  percha  is  precipitated  white  and  pure,  by 
alcohol,  from  solvents  which  mix  with  alcohol.  These  solvents  may 
then  be  recovered  from  their  alcoholic  mixtures  by  addition  of  water. 
The  solvents  tried  were  benzole  and  bisulphide  of  carbon,  the  benzole 
(from  coal-tar)  having  about  0"85  sp.  grav.  and  boiling  at  176°  to 
178°  F. 
It  is  stated,  on  the  authority  of  Kentf  that,  if  any  of  the  hydrocar- 
bons are  used  to  dissolve  gutta  percha,  the  solvent  cannot  be  fully 
expelled  without  decomposition  of  the  gutta  percha.  On  the  contrary> 
the  precipitate  formed  by  alcohol  in  benzole  solution  of  gutta  percha,, 
when  dried  on  the  water-bath,  was  found  to  lose  all  odor  of  benzole  in 
a  short  time,  and  to  possess  as  much  tenacity  as  samples  purified  by 
chloroform  or  bisulphide  of  carbon.  At  ordinary  temperature  the  pre- 
cipitate dried  very  slowly.f 
120  grains  of  gutta  percha  of  commerce  were  dissolved  by  aid  of  heat 
in  3  troyounces  of  benzole  (i  to  12);  the  solution  was  poured  upon  a 
filter  under  a  bell  jar  and  left  24  hours,  the  thermometer  being  60°  F. 
at  the  end  of  that  time,  when  the  gutta  percha  was  found  to  be 
deposited  in  a  white  granular  mass,  with  a  thin  granular  coating  of  pure 
*  "  Proceedings  of  Am.  Phar.  Asso.,"  1874,  p.  418. 
f  "Am.  Jour.  Sci."  (2),  vi,  246. 
X  According  to  the  "U.  S.  Dispensatory,"  p.  444,  complete  drying  requires  several 
weeks. 
