^Aprii,r'i9i5arm"}  Separation  of  Oxymethylanthraquinones.  149 
soluble  in  cold,  absolute  alcohol ;  soluble  in  concentrated  sulphuric 
acid  with  an  orange- red  color.  The  melting-point  (r.  h.)  was  not 
sharp,  gradual  liquefaction  taking  place  between  1600  and  165 °. 
The"  behavior  of  the  residue  by  the  color  test  already  described  may 
be  represented  as  follows : 
Residue  -f-  H2S04  =  orange  red;  +  HNOs  =  yellow;  +  H20  = 
yellow  solution  and  flocculent  precipitate. 
The  flocculent  precipitate  is  chrysophanic  acid  unchanged.10  Too 
much  nitric  acid  prevents  its  formation. 
Buckthorn  (Rhamxus  Fraxgula). 
As  a  source  of  emodin  fluidextract  of  buckthorn  was  used.  About 
25  Cc.  of  this  material  were  extracted  with  benzol  as  already 
described. 
Ammonium  Carbonate  Fraction. — A  little  color  was  removed  by 
this  reagent.   It  was  not  further  examined. 
Sodium  Carbonate  Fraction. — Practically  all  the  color  was  re- 
moved from  the  benzol  at  this  point  in  two  or  three  washings.  The 
color  was  passed  into  ether  and  the  ethereal  solution  evaporated. 
The  residue  was  orange  red  in  color ;  soluble  in  cold  absolute  alcohol ; 
soluble  in  concentrated  sulphuric  acid  with  a  decided  pink  color. 
The  melting-point  (r.  ti)  was  not  sharp;  liquefaction  extended  over 
a  range  of  about  50  and  was  complete  at  2400. 
The  behavior  of  emodin  by  the  color  test  as  applied  to  chryso- 
phanic acid  is  shown  thus : 
Residue  +  H2S04  =  intense  pink;  +  HN03  =  yellow;  +  H20  = 
pink  solution. 
Sodium  Hydroxide  Fraction. — The  slight  amount  of  color  left  in 
the  benzol  extract  was  removed  at  once  by  this  reagent.  The  fraction 
was  not  further  examined. 
Rhubarb. 
The  experimental  material  used  was  a  fluidextract. 
Ammonium  Carbonate  Fraction, — The  first  two  or  three  wash- 
ings of  the  benzol  extract  were  orange-colored,  after  which  prac- 
tically no  more  color  was  removed.  The  color  was  passed  into  ether, 
but  the  residue  was  small,  and  only  the  general  test  for  oxymethyl- 
Czapek,  "  Biochemie  der  Pflanzen  II,"  p.  529. 
