502 
Poison  Sumac. 
f  Am.  Jour.  Pharra. 
I  November,  1907. 
erties  of  this  juice.  The  earliest  was  Ishimatsu,  who  reported13  that 
the  lac  had  a  sweetish  odor,  an  irritating  taste,  that  it  burned  with  a 
luminous  flame,  which  emits  dense  black  smoke,  and  that  it  mixes 
with  fixed  oils  in  all  proportions.  He  found  that  the  lac  consisted 
of  a  substance  soluble  in  alcohol,  a  gum  soluble  in  water,  a  residue 
insoluble  in  alcohol  or  water,  and  small  quantities  of  water  and 
"  volatile  poison." 
His  method  of  separation  was  to  extract  the  milk-juice  with  abso- 
lute alcohol,  evaporate  the  solvent  and  dry  the  dissolved  portion  at 
ioo°  to  constant  weight.  The  portion  insoluble  in  alcohol  wras 
extracted  with  hot  water,  filtered,  the  filtrate  evaporated  and  the 
residue  dried  at  100°  and  weighed  as  gum.  The  residue  insoluble 
in  water  was  dried  at  ioo°  and  weighed.  Water  and  volatile  matter 
were  determined  by  difference. 
He  found  that  the  fresh  lac  yielded  58-24  per  cent,  of  substance 
soluble  in  alcohol.  This  alcohol-soluble  substance  was  brownish- 
black  in  color  and  had  the  same  odor  as  the  original ;  however,  it 
never  dries  to  a  varnish  as  that  does.  Lead  salts  of  this  compound 
were  prepared  and  analyzed,  from  which  the  formula  C2oH3002  was 
calculated.  No  experimental  proof  that  the  poisonous  constituent 
was  volatile  was  offered. 
In  1883  H.  Yoshida,14  employing  Ishimatsu's  method  of  separation, 
found  85-15  per  cent,  of  alcohol-soluble  substance  in  fresh  lac  of 
known  purity.  He  called  this  soluble  substance  urushic  acid  (from 
Ki-urushi,  Japanese  lac).  He  states  that  the  gum  is  identical  with 
gum  acacia,  and  reports  the  portion  insoluble  in  alcohol  or  water  as 
diastatic  matter.  He  proved  that  the  hardening  of  the  lac  was  due 
to  an  oxidizing  enzyme  acting  in  the  presence  of  moisture.  Like 
the  previous  investigator,  Yoshida  believed  that  the  poisonous  con- 
stituent of  the  lac  was  volatile,  but  offered  no  experimental  proofs 
for  this  supposition.  Yoshida  found  that  urushic  acid  was  soluble 
in  benzin,  ether  and  carbon  disulphide ;  less  easily  soluble  in  amyl 
alcohol  and  petroleum  of  high  boiling  point ;  insoluble  in  water ; 
sp.  gr.  0  9851  at  230.  It  remains  unchanged  at  1600,  but  slowly 
decomposes  with  carbonization  at  2000.  From  the  alcoholic  solution 
of  urushic  acid  many  salts  were  prepared,  most  of  which  were 
slightly  soluble  in  alcohol,  but  insoluble  in  water.    From  the  analy- 
13  Manchester  Lit.  and  Philos.  Soc.  [3]  1882,  249. 
"J.  Chem.  Soc,  1883,  472. 
