CHEMICAL  EXAMINATION  OF   THE  RUBIACEiE.  243 
8.  In  the  root  of  Rubia  tinctorum  there  are  present  rubichloric, 
citric,  ruberythric  and  pectic  acids,  alizarine,  purpurine  and  sugar. 
9.  In  the  herb  of  Galium  verum,  galitannic,  rubichloric,  and 
citric  acids  are  found.  The  two  latter  substances  also  exist,  to- 
gether with  small  quantities  of  tannic  acid,  in  Galium  aparine. 
Pectic  acid  has  only  been  found  in  the  roots  of  two  plants,  the 
Cephaelis  ipecacuanha  and  Rubia  tinctorum  ;  it  cannot  therefore 
be  considered  as  a  characteristic  constituent  of  the  plants  belong- 
ing to  the  family  Rubiacese.  The  same  is  the  case  with  cou- 
marine,  which  could  only  be  discovered  in  the  herb  of  Asperula 
odorata. 
The  same  must  be  said  of  the  organic  bases.  Bases  are  con- 
tained in  four  plants, — in  Cephaelis  ipecacuanha  (root,)  Chiococca 
racemosa  (root,)  Coffea  arabica  (seed)  and  Cinchona  scrobiculata 
(bark.)  In  the  other  plants  no  organic  bases  could  be  detected. 
All  the  plants  of  this  family  which  were  examined  contained  an 
acid,  the  aqueous  solution  of  which, — 
a,  is  colored  dark  green  by  perchloride  of  iron  ; 
b,  becomes  brown  on  the  addition  of  potash,  by  absorbing  oxy- 
gen from  the  air ; 
c.  The  acid  contains  14  equivs.  of  carbon  and  8  equivs.  of  hy- 
drogen, with  a  quantity  of  oxygen  varying  from  6  to  10  equivs. 
d.  All  these  acids,  as  far  as  they  have  been  examined  with  this 
view,  are  decomposed  by  the  action  of  acids,  alkalies  and  oxygen, 
or  heat,  and  furnish,  with  the  loss  of  2  equivs.  of  carbon  and  2 
equivs.  of  hydrogen,  a  product  of  decomposition  containing  6 
equivs.  of  hydrogen  to  12  of  carbon.  The  oxygen  in  these  pro- 
ducts amounts  to  5  or  6  equivs. 
These  acids  form  a  continuous  series ;  they  are  here  placed  one 
below  the  other,  proceeding  from  the  poorest  to  the  richest  in  oxy- 
gen. Some  of  them  possess  different  properties  with  the  same 
composition : — 
Ipecacuanhic  acid    =Cl4H806,  in  the  root  of  Cephaelis  ipecacu- 
anha. 
Caffeotannic  acid     =C14H807,  in  the  berries  of  Coffea  arabica 
and  the  root  of  Chiococca 
racemosa. 
Chinovatannic  acid  =C14H807,  in  the  bark  of  Portlandia  grandi- 
flora. 
Aspertannic  acid     =C14H808,  in  the  herb  of  Asperula  odorata. 
s 
