Am-/a°nU"iSlarm"}  The  Coloring  Principle  of  Poke  Berries.  3 
soon  changed  to  brownish  yellow.  HNOs  produced  the  same  effect. 
This  principle  is  evidently  the  phytolacein  of  Claussen.  (See  U.  S. 
Disp.,  16th  ed.,  p.  1 150.) 
The  Coloring  Principle. — Several  methods  of  obtaining  this  prin- 
ciple by  precipitation  were  tried  with  negative  results,  but  the  fol- 
lowing seemed  to  yield  the  purest  product.  The  juice  of  the 
ripe  berries  was  treated  with  an  equal  volume  of  alcohol  and  the 
mixture  filtered  after  24  hours.  The  filtrate  after  agitation  with 
stronger  ether  was  evaporated  in  a  vacuum,  the  residue  dissolved 
in  75  per  cent,  alcohol  and  filtered.  The  filtrate  was  evaporated 
under  reduced  pressure  and  yielded  a  bright  purplish  red  powder. 
This  powder  was  insoluble  in  absolute  alcohol,  ether  and  chloroform, 
but  was  readily  dissolved  by  water,  yielding  a  bright  red  or  purple 
solution,  according  to  the  strength  of  the  solution.  The  aqueous 
solution  was  turned  yellow  by  alkalies  and  reddened  again  by  the 
addition  of  an  acid. 
On  treating  the  aqueous  solution  with  an  excess  of  Fe2Cl6,  or 
chlorine  water,  it  was  decolorized ;  the  same  result  was  obtained 
by  strong  oxidizing  as  well  as  reducing  agents.  Boiling  the  solu- 
tion had  no  effect,  but  with  addition  of  HC1  and  continued  heat,  the 
solution  was  gradually  decolorized.  No  change  was  caused  by 
alum,  cream  of  tartar  or  stannous  chloride  ;  subacetate  of  lead  pro- 
duced a  light  purplish  precipitate.  An  attempt  to  obtain  the 
coloring  principle  by  this  reagent  was  a  failure,  due  to  the  decom- 
position after  separation  of  lead  by  hydrogen  sulphide.  On  heating 
the  aqueous  solution  with  Fehling's  solution,  it  gave  an  abundant  pre- 
cipitate of  cuprous  oxide.  By  previously  heating  with  diluted  acid, 
no  increase  in  the  reducing  power  on  Fehling's  solution  was  noted. 
An  aqueous  solution  with  a  little  alcohol  has  not  been  altered  by 
exposure  to  sunlight  for  14  days,  nor  has  any  appreciable  amount 
of  color  been  lost  by  exposing  writing,  in  which  it  served  as  ink,  to 
the  same  agent.  Failures  in  preparing  a  permanent  red  ink  from  the 
berries  have  largely  been  due  to  the  use  of  the  impure  juice,  and  here 
might  be  recommended  a  2  to  5  per  cent,  solution  of  the  coloring 
extract,  preserved  by  the  addition  of  ten  per  cent,  alcohol  and  one 
per  cent,  of  glycerin.  A  solution  of  the  coloring  principle  may  be 
used  as  an  indicator  in  the  titration  of  acids  ;  however,  a  rather  strong 
solution  must  be  used,  and  in  most  cases  phenolphthalein  is  preferable. 
