Aui.  Jour.  Pharm. 
April,  1893. 
Canaigre  Tannin. 
165 
yellow  coloring  substance  removed,  the  crystalline  principles  just 
mentioned  above  were  extracted. 
By  recrystallization,  the  second  one  was  obtained  sufficiently 
freed  of  fat  to  give  the  calcium  hydrate  and  the  ferric  chloride  tests 
for  chrysophanic  acid,  which  it  also  resembled  by  crystallizing  in  a 
square  form. 
The  extraction  with  petroleum  ether  did  not  manifestly  aid  in 
getting  a  lighter  colored  or  purer  tannin. 
All  these  tannins  gave  the  same  reactions  as  the  one  employed 
below. 
After  these  several  attempts  at  purification,  the  tannin  from  the 
water  extract  purified  by  means  of  lead  acetate  and  acetic  ether  as 
at  first  described,  was  employed  for  the  subsequent  work. 
This  tannin  was  porous,  yellow,  readily  soluble  in  water  and  free 
from  sugars. 
Upon  saturating  the  alcoholic  solution  with  ether,  it  was  thrown 
out  in  a  plastic  condition. 
A  one  per  cent,  solution  gave  the  following  reactions : 
Ferric  chloride,  
and 
Ammonium  hydrate,  .  .  . 
Ferrous  sulphate,  
Lead  acetate,  
Gelatin  and  alum  solution, 
Tartar  emetic,  
and 
Ammonium  chloride,  .  .  . 
Potassium  bichromate,  .  . 
Fehling's  solution,  .... 
Ammoniacal  silver  nitrate, 
Calcium  hydrate,  ..... 
Bromine  water,  
Ammonium  molybdate,  .  . 
Cobalt  acetate,  
Uranium  acetate,  ..... 
Ammouiacal  picric  acid,  . 
Ferric  acetate,  
Copper  sulphate,  
and 
Ammonium  hydrate,  .  .  . 
A  portion  of  the  solution  used  above  gave  with  bromine  water  a 
yellowish  precipitate,  which,  upon  collecting  and  washing  with 
1  green  ppt. 
'  brown  ppt. 
no  change, 
yellowish  ppt. 
yellow  ppt. 
}no  change, 
clouding,  becoming  a  flocculent  ppt. 
greenish-brown  ppt.,  darkening, 
reduced*, 
reduced. 
light  pink  ppt.,  turning  red  and  brown. 
first  yellow,  then  brown  ppt. 
no  change  in  color. 
yellow  ppt. 
f  crimson  color,  upon  standing,  a  red- 
l      brown  ppt. 
no  change  in  color. 
green  ppt. 
^  no  change. 
t  brown  ppt,  liquid  brownish-green. 
