1 



together in the ssane plant. Further tests with a solution 

 of the resin in dilute alcohol, and with a water solution 

 of the acid precipitated by adding sulphuric acid to a solution 

 of the resin in potassium hydroxide, led to the conclusion 

 that the acid is gallic acid. These tests were the following: 

 (1) Boiling with aa excess of potassium hydroxide gave a 

 black substaijce (tauromelanic acid), (2) The acid was 

 not precipitated by gelatin. (3) On addition of potassium 

 cyanide a transitory red color appeared which reappeared on 

 shaking with air. Gallic acid is distinguished from tannic 

 acid by tests (E) and (3). At later stages in the work the 

 potassium, barium, and sodium salts of gallic acid were ob- 

 tained, and finally the pure acid was made by decomposing the 

 sodium salt with sulphuric acid and cjrystallizing from water. 

 A portion of the acid so obtained was further purified by 



dissolving in absolute alcohol and pouring into absolute 



2 

 ether . The melting point behavior of the acid corresponds 



with that of gallic acid; it melted with decomposition at 



about 230°. For further identification, some of the acid 



was converted into an ester by the following process: It was 



dissolved in 80?S alcohol, hydrochloric acid gas was passed in, 



and the solution was heated an hour on the water bath. It 



1. Liebig's Annalen, CXI, p. 215. 



2. Uber Kategerbstoff , p. 20. 



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