626 
Coloring  Matters  of  the  Vine. 
Am.  Jour.  Pharm. 
Dec,  1892. 
I  have  proposed  and  used  several  ethereal  tinctures  for  dermal 
employment;  namely,  of  belladonna  ( tinct.  bellad.  aetherea),  of 
capsicum,  of  iodine  and  of  menthol.  I  expect  physicians  and 
pharmacists  will  find  other  useful  developments  of  ethereal  prepar- 
ations as  remedies  applied  to  the  skin. 
COLORING  MATTERS  OF  THE  VINE  :  AMPELOCHROIC 
.  ACIDS.1 
By  A.  Gautier. 
The  rapidity  with  which  grapes  ripen  in  Mid  Europe  led  the 
author  to  suppose  that  the  skin  pigment  to  which  the  color  is  due 
is  formed  by  the  oxidation  of  aldehydic  or  catecholic  substances, 
originating  in  the  leaves  and  travelling  thence  to  the  fruit.  This 
view  was  borne  out  by  the  effects  following  the  removal  of  the  leaves 
from  grapes  about  to  ripen,  or  by  the  partial  or  complete  stoppage 
of  the  circulation  between  the  leaves  and  stem,  the  grapes  in  the 
first  case  remaining  in  a  state  of  arrested  development,  whilst  in  the 
second  the  leaves  changed  in  color  to  red  or  brown,  and  not  the 
grapes. 
The  coloring  matter  of  leaves  thus  reddened  (from  plants  of  the 
Carignan  stock)  was  extracted  with  tepid  water  and  purified  by 
fractional  precipitation  with  lead  acetate,  with  which  it  finally 
formed  an  olive-green  precipitate ;  this,  on  decomposition  with 
hydrogen  sulphide  and  purifcation,  yielded  a  mixture  of  two  colored 
crystalline  acids,  a-  and  /9-ampelochroic  acids.  These  were  separated 
by  means  of  cold  water,  in  which  the  latter  alone  is  soluble. 
o-Ampelochroic  acid,  C19H16O10,  is  bibasic  and  forms  a  cochineal- 
colored  powder  consisting  of  ruby-red  plates  or  spindles,  soluble  in 
boiling  water  or  cold  alcohol,  but  insoluble  in  ether.  Its  solutions 
are  feebly  acid  to  litmus.  The  zinc  salt  is  olive-green,  and  turns 
indigo-blue  on  heating,  the  acid  zinc  salt  is  rose-colored  and  soluble; 
the  lead  salt  is  dark  green,  and  blackens  at  500;  the  acid  lead  salt 
is  wine  red.  Solutions  of  a-ampelochroic  acid  are  turned  greenish- 
brown  by  alkalis,  and  oxidize  on  exposure  to  the  air  ;  they  are  precipi- 
tated by  bromine-water;  they  give  a  greenish-black  precipitate  with 
ferric  salts,  a  dark-brown  precipitate  with  mercuric  nitrate,  a  yellow- 
ish-gray precipitate  with  silver  nitrate,  especially  in  presence  of 
1  Compt.  rend.,  114,  623-629  fjour.  Chem.  Soc,  October,  1892,  p.  1242. 
