700 
Rhus  Venenata  DC. 
(  Am.  Jour.  Pharm. 
(      October,  1920. 
A  good  grade  of  low-boiling  petroleum  ether  was  used  in  the  first 
extraction.  In  this  solvent  ethereal  and  non-volatile  fixed  oil  was 
obtained,  as  well  as  a  great  amount  of  chlorophyll.  On  standing 
a  white  waxy-like  substance  separated  out  of  the  petroleum  extract. 
By  spontaneous  evaporation  of  a  portion  of  the  petroleum  ex- 
tract a  yellowish  brown,  oily  residue  was  obtained.  This  residue, 
when  taken  up  with  neutral  alcohol,  is  neutral  in  reaction. 
The  alcoholic  solution  of  the  residue  was  optically  inactive, 
which  Pfaff  states  is  true  of  the  non-volatile  oil  causing  the  derma- 
titis. 
The  residue  from  the  petroleum  ether  extract,  when  taken 
up  with  alcoholic  potash  solution,  can  be  saponified.  No  glycerin 
is  liberated. 
To  confirm,  practically,  that  the  poisonous  principle  was  ob- 
tained in  the  petroleum  ether  extract,  the  same  was  applied  to  the 
inner  forearm  with  a  piece  of  cotton  and  allowed  to  remain.  In 
twenty-four  hours  inflammation  with  violent  itching  occurred  and 
in  thirty  hours  vesication  had  taken  place. 
An  alcoholic  solution  of  the  residue,  when  treated  with  a  solu- 
tion of  lead  acetate,  will  cause  precipitation  of  the  lead  salt  of  the 
oil  to  take  place.  By  treatment  of  this  lead  compound  with  hydro- 
gen sulphide,  Stevens  was  able  to  isolate  the  oil  from  the  Rhus 
toxicodendron. 
As  irritation  is  often  due  to  precipitation  of  proteins,  experi- 
ments were  made  to  precipitate  egg  and  blood  albumen  from  0.5 
per  cent,  solutions,  by  treatment  with  an  alcoholic  solution  of  the 
residue  from  the  petroleum  ether  extract.  Negative  results  were 
obtained.  More  extensive  experimentation  with  oil  obtained  from 
fresh  plants  is  hoped  to  be  carried  out  in  a  continued  article  by  the 
authors. 
In  the  presence  of  fixed  oil,  alkaloids  are  often  extracted  simul- 
taneously by  petroleum  ether,  but  no  alkaloids  could  be  extracted 
from  the  stems  or  leaves  of  this  plant. 
The  second  extraction  was  with  ether.  This  was  not  carried  out 
until  all  the  petroleum  ether  had  evaporated  from  the  marc. 
The  ether  extract  was  dark  red-brown  in  color,  which  yielded  a 
residue  of  the  same  color.  When  taken  up  with  neutral  alcohol 
the  reaction  was  unchanged.  Precipitation  took  place  when  the 
ether  extract  was  treated  with  lead  acetate  solution.  An  alcoholic 
solution  of  the  ether  residue  will  precipitate  a  resin  out  of  solution 
