AMjaH;  uSf" }  Adulteration  Notes,  etc.  1 7 
I  discard  ether,  because  chrysophanic  acid  is  much  more  soluble  in  it 
than  in  chloroform. 
The  application  of  the  test  is  as  follows  : — 
Let  the  required  number  of  pieces  of  white  blotting-paper,  about 
three  inches  square,  be  numbered  and  placed  on  a  pill  tile  or  glass 
slip  ;  in  one  corner  of  each  of  these  papers  place  about  five  grains  of 
the  several  rhubarb  samples  to  be  tested,  keeping  the  powder  as  much 
together  in  one  heap  as  possible ;  press  it  flat  and  smooth  with  the  aid 
of  a  piece  of  paper,  and  drop  cautiously  on  the  centre  of  the  powder, 
chloroform,  so  that  it  may  slowly  percolate  to  the  circumference, 
carrying  with  it  any  soluble  matters,  and  extend  nearly  one  inch  from 
the  powder,  taking  care  not  to  float  any  particles  over  or  under  the 
paper,  which  would  interfere  to  some  extent  with  the  succeeding  tests. 
Having  allowed  the  papers  to  dry,  it  will  be  found  that  a  yellow  stain 
of  varying  intensity  has  been  left  around  the  powder.  With  really 
fine,  bright- colored  East  Indian  rhubarb,  this  stain  is  scarcely  per- 
ceptible, but  cheaper  and  darker  samples  may  yield  a  brilliant  yellow, 
while  even  the  finest  bright  colored  English  powder  will  give  a  yellow 
stain  as  deep,  and  in  most  cases,  deeper,  than  the  darkest  East  In- 
dian. Should  turmeric  be  present  in  quantity  in  any  sample  it  will  at 
once  give  a  brilliant  yellow  stain,  in  tint  undistinguishable  from  that 
of  the  rhubarb,  but  which  may  readily  be  identified  by  the  following 
tests. 
Place  a  minute  pinch  of  biborate  of  soda  in  powder  on  that  portion 
of  the  paper  over  which  the  chloroform  had  extended,  and  which  pro- 
bably has  a  yellow  tint,  choosing  the  deepest  colored  part.  With  a 
glass  rod  deposit  a  single  drop  of  hydrochloric  acid  over  the  borax. 
In  a  few  seconds,  should  turmeric  be  present,  a  distinct  red  will  be 
produced,  which  is  changed  to  black  or  greenish  black  with  solution  of 
potash,  but  no  change,  except  a  slight  bleaching,  takes  place  if  the 
yellow  is  caused  by  rhubarb  colors  only.  A  drop  of  solution  of  pot- 
ash instantly  changes  the  yellow  stain  of  turmeric  to  a  more  or  less 
brown  tint,  while  a  pure  rhubarb  gives  a  bright  reddish-purple  color. 
For  delicate  operations,  a  saturated  solution  of  boracic  acid  is  pre- 
ferable to  the  powdered  borax,  so  that  any  obstruction  of  view  by  the 
white  powder  may  be  obviated  ;  but  it  is  necessary  in  either  case  to 
use  hydrochloric  acid,  which  quickens  and  intensifies  the  action  of  the 
boracic  acid. 
By  this  means  turmeric  can  readily  be  detected  in  rhubarb  contain- 
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