556  Turmeric  and  its  Coloring  Matter.  {AmNovr,'i8Sarm' 
grey  bark,  on  which  there  are  slight  rings  ;  though  that  met  with  in 
commerce  has  usually  a  yellowish  appearance,  owing  to  the  pieces  of 
the  root  becoming  rubbed  one  against  the  other. 
Under  the  bark  is  a  hard,  heavy  and  compact  substance  of  a  deep 
orange-yellow  color,  the  fracture  resembling  that  of  wax. 
The  root  has  the  odor  of  ginger,  and  a  warm,  bitter  and  somewhat 
acrid  taste,  owing  to  its  oil ;  it  imparts  to  the  saliva  a  yellow  color. 
The  powdered  root  was  formerly  given  medicinally  as  an  excitantr 
and  was  reputed  to  act  as  a  diuretic,  the  dose  given  in  old  Pharma- 
copoeias being  from  twenty  to  forty  grains.  It  is  largely  used  in 
India  and  China  in  the  arts  as  a  dye,  and  also  as  an  aromatic  condi- 
ment, it  being  one  of  the  ingredients  in  curry  powder. 
The  root  contains  a  small  percentage  of  volatile  oil,  resin,  brown 
extractive  matter,  starch  and  gum.  The  following  represents  the 
results  of  an  analysis  : — 
Yellow  volatile  oil   1 
Brown  extractive  matter   12 
Resin   10 
Gummy  matter   13 
Soluble  matter  in  alkaline  solution  ,   57 
Moisture,  etc   7 
100 
The  root  also  contains  from  two  to  three  per  cent,  of  curcumin, 
C14H1404,  a  yellow  coloring  matter,  which  is  soluble  in  oils,  alcohol 
and  fatty  liquids,  but  very  slightly  so  in  cold  water.  It  is  easily 
dissolved  in  an  alkaline  solution,  and  turns  a  deep  brown.  Jackson 
and  Menke  (see  Am.  Jour.  Phar.,  1882,  p.  398),  who  investigated 
curcumin  very  exhaustively,  found  it  to  be  a  diatomic  monobasic  acid. 
When  treated  with  weak  oxidizing  agents  it  was  found  to  yield 
vanillin.  They  succeeded  in  producing  the  following  products  from 
curcumin,  by  the  action  of  nascent  hydrogen,  and  of  bromine :  Cur- 
cumin dihydride,  an  anhydride  of  curcumin  dihydride,  tetrabromo 
curcumin,  curcumin  tetrabromide,  and  pentabromocurcumin  dibro- 
mide. 
The  brown  color  given  to  turmeric  paper  by  alkalies  depends  con- 
siderably on  the  strength  of  the  alkaline  solution  employed.  ■ 
Dilute  acids  will  restore  the  paper  to  its  original  color. 
The  powdered  root  when  treated  with  cold  water  yields  to  it  a  little 
of  the  coloring  matter,  enough  to  impart  a  dark  yellow  tint. 
