54 Trimble— Mangrove Tannin. 



composition with ether, and, after removing the latter, dis- 

 solving in water, and applying the usual reagents, a catechol 

 tannin was indicated. 



Hydrolysis. — 0.5 gramme, after boiling for three hours with 

 a two per cent, solution of hydrochloric acid (absolute HC1), 

 yielded a red insoluble decomposition product, and a sub- 

 stance capable of reducing Fehling's solution to an extent 

 which indicated 10.35 P er cent - of glucose. The above red 

 product was readily oxidized by nitric acid yielding a red- 

 brown solution which rapidly faded, and which with water 

 became paler, precipitation taking place at the same time. 

 The original product was not completely soluble in cold or 

 hot alcohol nor in ammonium hydrate. That which did dis- 

 solve in alcohol was not precipitated by a large quantity of 

 water. These properties indicated the presence of gallic acid, 

 ellagic acid and phlobaphenes. 



Composition. 



After repeated precipitation of the tannin until it was of 

 a light reddish-yellow color, it was dried at 120 and sub- 

 mitted to elementary analysis with the following results : 



(1) .2353 gramme gave .5188 C0 2 and .1023 H 2 0. 



(2) .2475 " " .5414 C0 2 and .1027 H 2 0. 



(3) -2556 " " -5577 C0 2 and .1070 H 2 0. 



indicating the following percentages : 



Calculated for 



Average. C25H25O11 C20H20O9 C27H24O11 



59.76 59.88 59.40 60.93 



4.69 4.99 4-95 4-68 



35-55 35-13 35-65 34-39 



The formula 025^50!! comes the nearest to representing 

 the average percentages obtained ; the formula C 20 H 2o O 9 is 

 that given by Dragendorff for rhatania-tannin ; and the for- 

 mula C 26 H 24 0„ is the one given by Rochleder for horsechest- 



