544 
ANALYSIS  OF  THE  LEAVES  OF  POISON-OAK. 
blue  coloration  produced  by  tincture  of  iodine  proved  the  pres- 
ence of  a  little  starch. 
IV.  The  remaining  substance  was  now  subjected  to  the  treat- 
ment at  a  moderate  temperature  with  very  dilute  hydrochloric 
acid  ;  after  exhaustion  the  leaves  had  now  lost  nearly  one-half 
their  original  weight.  The  solution  assumed  a  darker  color  on 
being  oversaturated  with  ammonia,  it  partly  gelatinized  (pectin) 
and  separated  a  white  powder,  which  proved  to  be  oxalate  of 
lime. 
V.  Not  having  detected  by  the  analysis  any  substance  to 
which  the  poisonous  qualities  of  poison-oak  might  be  attributed, 
the  author  made  a  series  of  experiments,  which  showed  a  volatile 
alkaloid  to  be  the  poisonous  constituent ;  it  was  obtained  by  the 
following  process : 
3  oz.  of  the  powdered  leaves  were  infused  with  hot  distilled 
water,  after  three  days  strained,  expressed,  the  liquid  evapo- 
rated to  3  oz.,  and  with  the  addition  of  caustic  potassa  carefully 
distilled  to  one-half.  The  clear  colorless  distillate  had  an  alka- 
line reaction  and  an  odor  resembling  henbane  or  hemlock.  It 
was  saturated  with  sulphuric  acid,  evaporated  and  treated  with 
a  mixture  of  equal  quantities  of  alcohol  and  ether,  which  left 
sulphate  of  ammonia  behind ;  the  solution  was  evaporated 
spontaneously,  distilled  with  caustic  potassa,  the  alkaline  dis- 
tillate neutralized  with  hydrochloric  acid,  and  a  precipitate 
could  now  be  obtained  with  chloride  of  platinum.  Want  of 
material  prevented  further  experiments. 
By  the  foregoing  analysis  the  leaves  of  Rhus  toxicodendron 
were  proved  to  contain  chlorophyll,  wax,  fat,  resin,  sugar, 
albumen,  gum,  pectin,  starch,  tannin  producing  a  green  color 
with  iron-salts,  oxalic  acid,  a  peculiar  indifferent  body,  and  a 
poisonous  alkaloid.* 
An  analysis  of  the  ashes  was  made,  which  proved  the  presence 
of  potassa,  soda,  lime,  magnesia,  alumina,  oxide  of  iron, 
chlorine,  sulphuric,  phosphoric,  silicic  and  carbonic  acids. — 
(  WitUteins  Vierteljahresschrift,  vii.,  348-359.)      J.  M.  M. 
*  [Note.  It  would  have  been  more  satisfactory  if  the  author  had  given  some 
physiological  evidence  of  the  poisonous  nature  of  the  alkaloid  substance  ob- 
tained. It  is  quite  interesting  to  hear  that  the  hitherto  intangible  venom  of 
this  plant  has  been  at  last  detected. — Ed.  Am.  Jour.  Phabm.] 
