Am.  Jour.  Pharm, 
July,  1905. 
'•}     Study  of  Fruit  and  Vegetable  Colors. 
309 
Turmeric 
Safflower 
Saffron 
Red  Saunders 
Logwood 
Madder 
Marigold 
much  lighter 
much  lighter 
slightly  lighter 
decolorizes 
no  change 
slightly  lighter 
decolorizes 
Commercial  Coal  Tar  Colors. 
One 
Two 
Three 
Four 
no  change 
no  change 
no  change 
no  change 
While  no  uniformity  can  be  observed  in  the  decolorizing  or  modi- 
fying effect  of  the  kaolin  upon  the  vegetable  colors  as  a  group,  it 
will  be  seen  that  an  additional  factor  is  afforded  for  the  differentia- 
tion and  identification  of  some  of  the  vegetable  and  fruit  colors. 
For  instance,  if  beet  juice  had  been  added  to  strawberry  syrup 
the  color  would  not  be  entirely  removed  by  filtration  through  kaolin 
and  the  addition  of  ammonium  hydroxide  solution  to  this  filtrate 
would  produce  a  greenish  color,  while,  if  only  the  natural  color  of 
the  strawberry  were  present,  complete  decolorization  would  occur. 
The  reducing  effect  of  nascent  hydrogen  produced  by  the  action 
of  hydrochloric  acid  upon  metallic  zinc,  and  of  solution  of  stannous 
chloride,  which  plays  such  an  important  part  in  the  various  schemes 
for  the  identification  of  the  synthetic  colors,  was  then  tried  with  the 
view  of  ascertaining  what,  if  any,  effect  such  reagents  would  have 
upon  vegetable  colors. 
The  zinc  and  hydrochloric  acid  reaction  was  produced  by  adding 
I  c.c.  of  31-9  per  cent,  hydrochloric  acid  to  5  c.c.  of  the  color  solu- 
tion contained  in  a  test  tube  similar  to  that  previously  described, 
and  then  adding  about  0-5  grammes  of  metallic  granulated  zinc  and 
allowing  the  reaction  to  continue  for  at  least  thirty  minutes  before 
making  any  observations. 
The  solution  of  stannous  chloride  was  made  by  dissolving  5 
grammes  of  pure  tin  foil  in  30  grammes  of  31-9  per  cent,  hydro- 
chloric acid  and  afterward  diluting  the  solution  with  water  to  make 
50  grammes.  One  cubic  centimeter  of  this  solution  was  added  to  5 
c.c.  of  the  color  solution  in  a  test  tube  similar  to  the  one  described 
previously,  and  any  changes  were  noted  after  the  mixture  had  been 
allowed  to  stand  for  five  minutes. 
