244 
THE  SOAP-BARE  OF  SOUTH  AMERICA. 
gr.,)  according  to  the  method  followed  by  Lebeuf,  Bochleder, 
and  Schwarz,  the  saponine  was  extracted.  This  substance  is 
characterized  by  its  lasting  irritating  smell,  and  by  producing 
sneezing  :  in  some  cases  a  special  aromatic  flavor  is  perceived. 
It  is  remarkable  how  small  a  particle,  a  mere  homoepathic  dose, 
is  sufficient  to  change  a  large  quantity  of  oil  into  an  emulsion. 
The  saponine  has  likewise  the  power  of  reducing  gold  from  its 
chloride. 
The  extract  of  the  soap-bark,  prepared  as  mentioned  above, 
undergoes  a  spontaneous  change,  when  exposed  to  the  influence 
of  the  atmosphere  for  several  weeks.  The  clear  solution  is  then 
transformed  into  a  colorless,  thick,  but  transparent  jelly,  with 
a  slight  acid  reaction.  Its  property  of  making  emulsions  is  not 
the  least  diminished,  but  it  has  lost  the  power  of  reducing  gold 
and  copper  as  before,  and  the  reaction  on  the  mineral  chameleon 
proceeds  very  slowly.  In  short  to  explain  the  change,  it  is 
sufficient  to  say,  that  by  absorption  of  oxygen  from  the  air,  the 
substance  extracted  by  water  has  been  oxidised. 
To  conclude,  it  appears  that  the  soap-bark  retains  two  sub- 
stances, saponine,  and  pectine,  both  soluble  in  cold  water,  and 
equally  endowed  with  the  faculty  of  making  emulsions  with  oils 
and  fatty  substances.  The  large  quantity  of  isolated  pectine  in 
the  soap-bark  is  explained  by  the  separation  from  the  lime 
during  vegetation.  The  spontaneous  oxidation  has  transformed 
the  pectine  into  the  gelatinous  acids,  the  pectosic  acid  and 
pectinic  acid. 
Several  years  ago,  in  1832,  M.  Braconnot,  in  his  inquiries  as 
to  the  transformations  of  several  vegetable  substances  into  a 
new  principle  by  the  influence  of  concentrated  nitric  acid,'  re- 
marked that  he  found  the  saponine  in  the  bark  of  the  Chicot  de 
Canada,  or  Gymnocladus  Canadensis,  Lam.  He  says  that  it  is 
possible  to  substitute  this  bark  (and  also  its  leaves)  for  the  soap- 
wort  of  the  Levant.  This  tree  is  30  or  40  feet  high,  able  to 
stand  our  winters,  and  easily  cultivated.  I  have  also  another 
sample  of  a  bark  containing  saponine  and  pectine,  which,  when 
combined,  are  excellent  for  washing  purposes. 
Besides  this,  a  kind  of  soap-bark  is  mentioned  in  the  proceed- 
ings of  the  Boston  Society  of  Natural  History  for  1855  (see 
also  the  Edinburgh  New  Philosophical  Journal,  vol.  li.,  p.  201.) 
