78 New Process for preparing Gallic Acid. 



Art. IX. — A New Process for preparing Gallic Acid; by Ed- 

 ward N. Kent. 



TO THE EDITORS OF THE AMERICAN JOURNAL OF SCIENCE AND ARTS. 



Gentlemen — During a recent examination of black ink, which 

 had been prepared by exposure to the atmosphere for three months, 

 I found it contained a quantity of free gallic acid, protosulphate 

 of iron, and pertannate of iron. 



Having previously experienced the inconvenience of waiting 

 two months to prepare gallic acid by the old process, and as it is 

 not an article of commerce, it occurred to me that if the acid in 

 the ink could be easily isolated, it would form a valuable process 

 for its preparation when wanted for immediate use, as ink can 

 always be readily obtained containing the acid ready formed. 



I therefore agitated a pint of ink with an equal measure of 

 sulphuric ether,* left it at rest for a few moments to separate, and 

 then decanted the ether, and found it had taken up gallic acid to 

 the exclusion of the other constituents, except a light yellow 

 color and odor of cloves, these having been put into the ink. I 

 then distilled the ethereal solution nearly to dryness; the residue 

 crystallized on cooling. I returned the distilled ether on the ink, 

 and repeated the process the third time, and after crystallizing 

 three times and drying, obtained twenty eight grains of colorless 

 gallic acid. 



I then distilled off from the ink a little remaining ether, and 

 the ink was left as good for ordinary purposes as before ; and the 

 only expense in the preparation of the acid was the loss by evap- 

 oration of about one ounce of the ether. 



Most of the inks which I have tried gave the same result when 

 treated with ether. Some however which have been prepared 

 by boiling the nutgalls, and exposure for a few days only, yielded 

 principally tannic acid. It is therefore advisable to test the ink 

 with gelatine before attempting to prepare gallic acid by this 

 process. Yours, very respectfully, 



Edward N. Kent. 



New York, October 9th, 1843. 



* I have repeated Mr. Kent's experiment successfully : care must be had that the 

 ether is quite free from alcohol, which commercial ether never is. As gallic acid 

 is more soluble in alcohol than in ether, the process .is only partially successful 

 when alcohol is present. — B. S. Jr. 



