GALLIC ACID, 



An alcoholio solution of the resin was Just neutralized 

 with potassium hydroxide. During the titt«tion, the solution 

 rapidly "became dark brown. After neutralization it was 

 shaken with ether; the water solution remained hrown while 

 the ether layer was nearly colorless and contained practically 

 no dissolved substance. A portion of the water solution 

 of the potassium salt on being acidified with sulphuric 

 acid aud standing over night, deposited a slight precipitate. 

 The solution of the potassium salt gave a heavy precipitate 

 with lead acetate somewhat similar to the original lead pre- 

 cipitate A, and alao slight precipitates with salts of zinc, 

 mercury, copper, an 1 TrkyrrysLXx. silver (with reduction). It 

 gave a bluish-black color with impure ferrous sulphate and 

 a dark color with ferric chloride. It reduced ammoniacal 

 silver nitrate and Fehling solution. These experiments in- 

 dicated the presence of a tannin compound. An alcoholic 

 solution of the reain gave the same color reactions with 

 iron salts as did the potassium salt. To determine which. 

 one of the tannin compounds was present was a matter of some 

 difficulty since the di- and trl-hydroxybenzO'.c acids have 

 in general the same color reactions. The p- isence of other 

 plant substances in the solution also interferes with the 

 color tests, and finally, a substance which gives a blue color 

 with iron salts and one giving a green color may be found 



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