4 
ACTIVE  PRINCIPLE  OF  RHUS  TOXICODENDRON. 
ON  THE  ACTIVE  PRINCIPLE  OF  RHUS  TOXICODENDRON. 
By  John  M.  Maisch. 
Notwithstanding  the  poisonous  qualities  of  Ehus  Toxicoden- 
dron have  been  known  for  a  long  time,  it  was  not  until  the  year 
1857  that  an  analysis  of  its  constituents  were  made  by  Dr. 
Joseph  Khittel,  which  was  published  in  Wittstein's  Vierteljah- 
resschrift,  vii.  348-359.  A  condensed  translation  of  this  paper 
appeared  in  the  American  Journal  of  Pharmacy,  1858,  p.  542- 
544.  According  to  this  author,  the  activity  of  the  leaves  of 
the  poison  oak  depend  on  a  volatile  alkaloid,  which  he  ob- 
tained by  distilling  the  concentrated  infusion  of  the  powdered 
leaves  with  caustic  potassa,  neutralizing  the  distillate  with  sul- 
phuric acid,  evaporating  the  liquid,  and  treating  the  residue 
with  a  mixture  of  equal  quantities  of  ether  and  alcohol,  where- 
by sulphate  of  ammonia  was  left  behind  ;  the  ethereo-alcoholic 
solution  was  evaporated  spontaneously,  distilled  with  caustic 
potassa,  and  an  alkaline  liquid  obtained,  which  could  be  neu- 
tralized with  hydrochloric  acid,  and  then  yielded  a  precipitate 
with  chloride  of*  platinum. 
Since  that  time,  I  have  not  met  with  another  investigation. 
I  may  as  well  state  at  the  outset,  that  my  results  are  entirely r 
at  variance  with  those  of  Dr.  Khittel ;  and  it  may,  therefore, 
not  be  out  of  place  to  criticise  the  above  process  now. 
It  is  well  known  that  the  exhalations  of  Ehus  Toxicodendron 
exert  a  poisonous  influence  on  the  human  body ;  the  poisonous 
principle  must,  therefore,  be  volatile,  and,  at  the  same  time,  be 
naturally  in  such  a  loose  state  of  combination  as  to  be  con- 
tinually eliminated  and  separated  with  the  usual  products  of 
vegetable  exhalations.  It  is  natural  to  suppose  that,  during  the 
process  of  drying,  the  greatest  portion  of  the  poisonous,  prin- 
ciple should  be  lost.  This  loss  must  be  still  greater,  if  the 
dried  leaves  are  powdered,  a  hot  infusion  prepared  from  them, 
and  this  infusion  evaporated  down  to  the  original  weight  of 
the  dried  leaves.  It  is  obvious  that  Dr.  Khittel  could  not  have 
selected  a  better  method  for  obtaining  the  least  possible  quan- 
tity of  the  poisonous  principle,  if,  indeed,  it  could  be  obtained 
by  this  process  at  all. 
