AVnTmTM,|  Adulteration  Notes,  etc.  19 
therapeutic  value  and  chemical  characteristics  much  like  our  own  na- 
tive root,  and  gives  up  about  as  much  color  to  chloroform. 
Of  the  character  of  the  stain  given  by  inferior  or  false  rhubarbs, 
excepting  its  intensity,  as  compared  with  that  produced  by  fine  East 
Indian  root,  I  have  unfortunately  been  unable  to  distinguish  any  pe- 
culiarity such  as  would  lead  to  its  unfailing  detection  :  still  the  con- 
stancy of  the  variation,  according  to  the  kind  of  rhubarb  used,  is  such, 
I  think,  as  ought  to  give  a  reliable  index  of  quality. 
A  powder  offered  as  East  Indian  rhubarb,  of  pale  brilliant  color, 
having  the  usual  characteristics  of  that  variety,  should  give  but  an  ex- 
ceedingly pale  yellow  tint.  Should  a  deep  yellow  be  given  I  would 
suspect  English  or  French  contamination.  An  East  Indian  powder 
of  a  dark  hue  however  may  give  almost  as  deep  a  color  as  English, 
and  still  be  genuine ;  though  by  this  color  I  would  judge  it  was  the 
product  of  unpicked  roots,  trimmings,  or  even  worm-eaten  pieces,  ac- 
cording to  the  depth  of  tint. 
The  few  specimens  of  Turkey  rhubarb  I  have  been  enabled  to  ex- 
periment upon,  through  the  kindness  of  several  friends,  yield  results 
like  East  Indian, 
The  cause  of  this  varying  color  yielded  by  different  rhubarbs  is 
somewhat  obscure,  the  chemistry  of  the  drug  being  as  yet  far  from 
satisfactorily  elucidated.  Chloroform  seems  to  dissolve  out  chiefly  the 
resinous  principles  erythroretin,  phseoretin,  (and  aporetin  ?)  which 
exist  in  varying  quantity  in  different  parts  and  varieties  of  root, 
while  the  crystalline  principles  chrysophanic  acid  and  emodin  are 
left  behind. 
Beautiful  aggregates  of  granular  crystals  of  chrysophanic  acid  may 
be  easily  obtained  by  percolating  ether  after  chloroform  through  East 
Indian  rhubarb,  and  allowing  the  ether  to  evaporate  spontaneously. 
It  is  noteworthy  that  English  and  French  rhubarbs  treated  thus  yield 
no  such  crystals,  the  residue  being  a  minute  quantity  of  pale  browa 
gummy  extractive ;  though  from  ail  varieties  distinct  brownish  acicu- 
lar  crystals,  probably  emodin,  will  be  observed  on  the  sides  of  the 
evaporating  basin. 
It  may  be  suggested  that  chrysophanic  acid  which  is  recognized  as 
the  chief  principle  of  rhubarb,  by  continued  exposure  to  atmospheric 
influences,  absorbs  oxygen  and  is  converted  into  what  is  at  present 
known  as  the  resins  erythroretin  and  phaeoretin,  which  some  have 
not  accepted  as  distinct  principles,  but  assert  to  be  "  nothing  but  im- 
