66 
THE TANNINS. 
the history and discovery of tannin ; therefore it is 
not surprising that in 1804 we find a contribution by 
Trommsdorff on the nature of this astringent principle 
in galls. His investigations somewhat resembled those 
of Deyeux. The work was divided into fifty-five ex¬ 
periments, in which he studied the precipitates caused 
by hydrochloric and sulphuric acids on infusion of galls, 
and added the observation that acetic and phosphoric 
acids likewise caused precipitates with tannin, while 
oxalic, tartaric, and malic acids caused no precipitates. 
He noticed the effect of tannin solution, after removal 
of gallic acid, on litmus-paper, and further endeavored 
to obtain pure tannin by Proust’s method of precipi¬ 
tation with potassium bicarbonate, but found much tan¬ 
nin in the filtrate, and finally concluded that the pre¬ 
cipitate contained calcium and that Proust erred in his 
new method. The same conclusions were reached in 
regard to Proust’s other methods by precipitation with 
mineral acids. This long, and at that time valuable, 
series of experiments was abruptly terminated without 
drawing conclusions, as he hoped to continue his inves¬ 
tigations. 
After the above communication no important results 
are recorded until Serturner, an apothecary in Eim- 
beck, during the year 1812, published his experiments, 
in which he established the absence of nitrogen, and 
made some observations on the action of alkalies on 
tannin, and the change into gallic acid. As, however, 
his results were in part a repetition of those obtained 
by previous investigators, his work was not kindly 
criticised by Gehlen. 
While there were a number of contributions on this 
