ACTIVE  PRINCIPLE  OP  RHUS  TOXICODENDRON. 
7 
bicarbonate  of  potassa,  and  treated  with  alcohol  and  ether  with 
precisely  the  same  results  as  stated  above ;  it  is  not  impossible 
that  large  quantities  of  a  mixture  of  alcohol  and  ether  will 
dissolve  minute  traces  of  sulphate  of  ammonia. 
It  was  evident  now  that  our  Ehus  Toxicodendron  does  not 
contain  any  volatile  alkaloid. 
Another  lot  of  vigorous  leaves  was  now  collected,  enclosed 
in  a  tin  box,  and  a  number  of  moistened  test  papers  introduced. 
The  next  morning,  it  was  observed  that  the  curcuma  and  red 
litmus  papers  were  unaffected,  but  that  the  blue  litmus  papers 
had  been  colored  strongly  red.  This  single  experiment  was  at 
once  a  conclusive  proof  that  the  exhalations  of  these  leaves  con- 
tained a  volatile  acid,  and  that  the  poisonous  properties  were 
most  likely  due  to  it. 
These  leaves  were  now  bruised  with  six  per  cent,  of  their 
weight  of  slaked  lime,  and,  after  maceration  with  a  sufficient 
quantity  of  water,  expressed,  again  macerated  and  expressed, 
and  the  liquor  reserved  for  a  few  days  for  further  investigation. 
In  the  meantime,  the  residue  in  the  retort  from  the  previous 
lot  was  mixed  with  sufficient  sulphuric  acid  to  impart  a  strongly 
acid  reaction,  and  then  subjected  to  distillation,  the  distillate 
being  collected  in  water  containing  carbonate  of  baryta  in  sus- 
pension. This  distillate  had  nearly  the  same  odor  as  the  dis- 
tillate obtained  by  lime,  and  the  conclusion  arrived  at  before, 
that  the  odorous  compound  was  a  distinct  body,  was  thereby 
verified.  The  distillation  was  soon  stopped,  because  this  pro- 
duct was  merely  intended  for  experiments,  and  to  ascertain 
whether  the  previous  continued  heating  with  lime,  had  pro- 
duced a  change  in  the  acid  or  not.  During  this  process,  a 
slight  eruption  appeared  above  the  wrists  on  both  my  arms, 
but  was  ascribed  to  the  extremely  hot  weather.  It  was  treated 
with  subacetate  of  lead,  and  no  further  notice  taken  of  it. 
The  solution  of  the  baryta  salt,  thus  obtained,  was  tested 
with  various  reagents :  nitrate  of  silver  produced  a  slight 
milkiness,  removable  by  nitric  acid  ;  on  standing,  a  copious 
black  precipitate  was  obtained ;  bichloride  of  mercury,  after 
some  time,  produced  a  white  precipitate,  then  supposed  to  be 
calomel ;  bichloride  of  platinum  an  extremely  slight  deposit  • 
