THE  SOAP-BARK  OF  SOUTH  AMERICA. 
241 
THE  SOAP-BARK  OF  SOUTH  AMERICA. 
By  Professor  S.  Bleekrode,  Delft,  Holland. 
Several  months  ago,  a  peculiar  bark  (Quillaia  saponaria}  was 
introduced  into  the  European  trade,  and  recommended  to  be 
employed  instead  of  soap,  for  washing  and  cleaning  printed 
goods,  woollens  and  silks,  and  especially  for  the  delicate  colors 
of  ladies'  dresses,  &c. 
The  soap-bark  is  externally  black  colored,  but  internally  the 
liber  consists  of  concentric  layers  of  yellowish  white.  The  bark 
is  remarkable  for  its  density,  as  it  sinks  in  water.  The  cause 
of  this  is  the  great  quantity  of  mineral  substances  which  it  con- 
tains :  thus  the  internal  layer  yielded  13«935  per  cent,  of  ash, 
dried  at  a  low  temperature,  and  18*50  per  cent,  when  dried  at 
100°  C.  The  ash  consists  almost  entirely  of  carbonate  of  lime, 
which  forms  12«60  per  cent,  of  the  13«935,  and  appears  as  small 
crystalline  needles,  isolated  or  in  groups,  in  the  cells  of  the 
liber,  not  only  between  its  concentric  rings,  but  in  every  part  of 
it.  These  glitter  in  the  sun,  resembling,  under  the  microscope, 
the  arragonite  form  of  the  crystallized  carbonate  of  lime. 
Relative  to  the  great  amount  of  lime,  it  may  be  remarked  that 
this  mineral  is  generally  characteristic  of  plants,  in  which  muci- 
laginous or  pectinic  substances  are  found  abundantly :  thus  the 
grains  of  the  quince  (cydonia)  contain  10  per  cent,  of  carbonate 
of  lime,  and  are  remarkable  for  their  large  quantity  of  jelly. 
When  the  internal  white  layers  of  the  bark  are  soaked  and 
macerated  in  water,  at  the  ordinary  temperature,  a  clear  solution, 
without  any  alkaline  or  acid  reaction,  is  soon  formed  ;  this 
becomes  slightly  turbid  by  the  action  of  the  air.  When  shaken, 
a  heavy  scum  is  produced.  The  bark  loses  nearly  20  or  25  per 
cent,  in  the  water.  I  have  prepared  an  extract  from  four 
drachms  in  nearly  one  pint  of  water,,  and  one  part  of  this  was 
sufficient  to  make,  with  sixty-eight  times  its  weight  of  olive  oil, 
a  perfect  cream-like  emulsion,  which  does  not  become  separated, 
even  after  several  months.  By  mixing  equal  volumes  of  the 
bark  extract  and  of  oil,  the  same  emulsion  is  formed  without 
change  of  volume,  but  in  a  short  time  the  oil  is  changed  into  a 
thick,  pure,  white,  cream-like  substance,  swimming  upon  the 
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