24 
Sterculia  Gum. 
Am.  Jour.  Pharm. 
Jan.,  1S90. 
closest  resemblance  to  the  produce  of  the  Indian  species  of  Sterculia 
just  described,  as  is  seen,  indeed,  from  Dr.  Fluckiger's  description. 
Lock  states  that  it  is  formed  in  great  quantity,  and  commonly  finds 
its  way  into  parcels  of  Senegal  gum.  If  Fluckiger's  conclusions  as 
to  its  utility  are  justifiable,  it  is  singular  that  it  has  not  come  into  use, 
but  the  present  writer  can  find  no  further  allusion  to  it  anywhere. 
The  following  notes  on  "  African  Tragacanth  "  from  this  species  are 
abstracted  from  a  paper  by  Dr.  Fliickiger  (Pharm.  Journ.  [2],  x, 
641). 
The  substance  experimented  upon  consisted  of  "  irregular,  knobby, 
undulated,  droppy,  or  stalactitic  masses,  more  or  less  bubbly  or  cav- 
ernous, often  exceeding  an  ounce  in  weight,  of  a  pale  yellowish  hue 
or  almost  colorless,  in  small  fragments  nearly  transparent,  but  seen  in 
mass  somewhat  opaque  by  reason  of  innumerable  cracks,  which  also 
render  it  more  brittle  than  true  tragacanth.  Each  mass  is,  in  fact, 
traversed  by  curved  fissures  answering  to  successive  protrusions  of 
gum.  Fragments  of  bark  are  often  adherent  to  the  flat  or  inner  side 
of  the  pieces. 
"  With  twenty  parts  of  water  coarsely  powdered  African  tragacaDth 
forms,  like  common  tragacanth,  a  thick,  tasteless  jelly  ;  with  forty 
parts  of  water  the  jelly  becomes  more  fluid.  Only  a  very  small  quan- 
tity of  gum  is  really  dissolved  in  the  water ;  the  filtered  liquid  is  not 
precipitated  either  by  neutral  acetate  of  lead  or  by  absolute  alcohol,1 
but  on  addition  of  basic  acetate  of  lead  it  becomes  a  little  turbid. 
The  jelly  itself  reddens  litmus  paper.  Neither  thin  slices  of  the  dry 
tragacanth  nor  the  jelly  exhibit  any  trace  of  cellular  structure,  or  of 
starch,  even  when  examined  in  polarized  light  by  means  of  a  micro- 
scope. In  this  respect  the  tragacanth  of  Sterculia  differs  from  that 
of  Astragalus.  As  a  means  of  promoting  the  adhesiveness  of  pilu- 
lar  masses,  I  find  the  former,  whether  in  the  form  of  powder  or  mucil- 
age, as  advantageous  as  ordinary  tragacanth. 
"  The  fine  powder  on  exposure  for  some  days  to  a  temperature 
of  212°  F.  loses  20*5  per  cent,  of  its  weight.  The  formula 
C12H22On  +  5H20  would  exactly  require  20*5  per  cent,  of  water.  .  .  . 
Upon  incineration,  the  dried  powder  leaves  7*8  per  cent,  of  ash,  of 
which  the  prevailing  constituent  is  carbonate  of  calcium.   .  .  . " 
Dr.  Fliickiger  then  reports  the  result  of  an  ultimate  analysis  of  the 
1  The  formation  of  a  ppt.  by  this  reagent  is  rendered  almost  impossible 
in  such  dilute  solution. — J.  H.  M. 
