Am.  Jour.  Pharm.  \ 
February,  1906.  f 
Japanese  Lac. 
63 
no  effect  upon  the  thick  inner  skin  of  the  hand,  but  to  prevent  its 
transmission  to  other  parts  it  should  be  removed  as  soon  as  possi- 
ble. For  example,  by  accident  some  of  the  benzin  solution  was 
thrown  into  one  eye  and  over  one  hand.  The  eye  was  thoroughly 
washed  with  benzin  and  alcohol,  but,  in  my  anxiety  for  the  eye,  the 
hand  was  forgotten  for  twenty  or  thirty  minutes,  when  it  was  thor- 
oughly washed  with  benzin  and  alcohol,  followed  by  soap  and  sand. 
The  eye  escaped  without  further  inconvenience  than  that  caused  by 
the  benzin,  but  in  thirty-six  hours  the  surface  of  the  hand  became 
slightly  swollen,  itched  considerably  for  a  week,  and  then  appeared 
to  be  covered  with  a  thin,  dry  scale,  which  finally  disappeared. 
Since  then  I  have  tested  different  parts  of  the  substance  to  deter- 
mine whether  or  not  they  were  all  poisonous,  by  cutting  a  hole 
6  m.m.  in  diameter  in  a  piece  of  gum  paper,  pasting  this  on  the  arm 
and  applying  the  substance  to  the  opening.  In  from  thirty  minutes 
to  one  hour  the  paper  was  removed  and  the  spot  washed  with  ether 
or  benzin.  When  the  substance  was  poisonous,  the  spot  became 
red  and  began  to  itch  within  thirty  hours.  From  three  to  five 
vesicles  usually  appeared.  The  itching  was  not  intense,  usually 
lasting  only  a  few  minutes  at  a  time.  A  dry  scale  formed  over  the 
surface  and  remained  for  several  weeks  after  all  irritation  ceased. 
The  poison  has  not  at  the  present  time  been  isolated  in  a  pure 
condition. 
Dr.  Jadassohn  and  his  assistants,  Drs.  Winkler  and  Schulz,  made 
twenty- six  tests  with  parts  of  the  lac  obtained  under  different  con- 
ditions. 
Only  that  portion  which  is  completely  soluble  in  benzin  is  poisonous 
and  this  we  have  previously  seen  has  been  separated  by  shaking  out 
the  benzin  solution  with  alcohol,  into  two  parts,  one  soluble  in 
alcohol  and  poisonous,  the  other  insoluble  in  alcohol  but  soluble  in 
benzin  and  non-poisonous.  I  have  elsewhere  stated  that  by  frac- 
tional precipitation  with  lead  acetate  a  partial  separation  of  the 
poison  was  obtained,  but  that  I  did  not  consider  it  a  practical 
method. 
After  the  above  experiments  with  the  poison  were  made  I 
received  from  Dr.  F.  Pfaff  a  reprint  of  his  article  "  On  the  Active 
Principle  of  Rhus  Toxicodendron  and  Rhus  venenata."1    As  the 
1  The  Journal  oj  Experimental  Medicine,  Vol.  II,  No.  2,  p.  181,  1897. 
