ACTIVE  PRINCIPLE  OF  RHUS  TOXICODENDRON. 
9 
either  in  the  cold  or  on  boiling ;  but  treated  with  the  solution 
of  a  salt  of  the  new  acid,  a  white  precipitate  is  produced,  which 
gradually,  but,  on  boiling,  instantly  changes  black  ;  nitric  acid 
dissolves  it  readily. 
Red  oxide  of  mercury  is  dissolved  by  the  boiling  acid ;  the 
solution,  filtered  while  hot,  deposits,  on  cooling,  nearly  all  the 
"  salt,  leaving,  however,  enough  in  solution  to  affect  hydrosul- 
phuric  acid  considerably.  This  white  mercuric  salt  is  the  same 
as  the  white  precipitate  occurring  in  solutions  of  a  salt  of  the 
new  acid  with  bichloride  of  mercury,  and  it  is  not  reduced 
either  on  standing  or  by  boiling. 
Protoxide  of  lead  is  readily  taken  up  by  the  boiling  acid, 
forming  a  solution  of  a  strong  alkaline  reaction,  which,  on 
cooling,  precipitates  most  of  the  salt  in  white  flocks,  leaving 
the  liquid  decidedly  alkaline ;  the  salt  is  taken  up  by  dilute 
nitric  acid. 
Carbonate  of  copper  dissolves  in  the  boiling  acid  to  a  bluish 
green  solution,  which  forms  no  precipitate  on  cooling. 
Neutral  sesquichloride  of  iron  is  not  affected  in  color,  either 
by  the  pure  acid,  or  by  one  of  its  salts. 
Permanganate  of  potassa  is  readily  reduced. 
Chromate  of  potassa  \$  not  reduced  to  chromic  oxide,  on  boil- 
ing, either  with  the  free  acid  or  one  of  its  salts. 
Comparing  all  these  reactions  with  those  of  formic  acid,  it 
will  be  seen  that  only  the  behaviour  to  chloride  of  gold,  and  the 
reduction  of  metallic  gold  from  the  solution  are  identical ;  in 
the  sparing  solubility  of  the  lead  salt,  the  two  acids  likewise 
resemble  each  other.  This  acid  has  more  reactions  in  common 
with  acetic  acid,  among  the  most  prominent  of  which  are  the 
slight  alkaline  reaction  of  their  salts  with  alkalies  and  alkaline 
earths,  and  the  strong  alkaline  reaction  of  the  (basic  ?)  lead 
salt. 
But  the  behaviour  of  this  acid  and  its  salts  to  oxide  of  silver, 
nitrate  of  silver,  oxide  of  mercury,  and  corrosive  sublimate,  dis- 
tinguish it  readily  from  both  formic  and  acetic  acid. 
Taking  all  the  reactions  together,  it  is,  unquestionably,  a  new 
organic  acid,  for  which  I  propose  the  name  of  Toxicodendric 
acid. 
