Trimble.— Mangrove Tannin. 



53 



water, alcohol, and commercial ether. It was partly precipi- 

 tated from its aqueous solution by saturation with common 

 salt. That not precipitated was removed by agitation with 

 acetic ether, and, although lighter in color, it was found to be 

 identical with the darker portion precipitated by the salt. 



The following are the reactions of the mangrove tannin, in 

 one per cent, solution, with the usual reagents. There is 

 added for comparison the behavior of a similar solution of 

 gallo-tannic acid. 



Reagent. 

 Sulphuric acid ( i to 9 of 



water 1, 

 Bromine water, 



Ferric chloride, 



and 

 Ammonium hydrate, 



Tartar emetic, 



and 

 Ammonium chloride, 



Calcium hydrate, 



Concentrated sulphuric 

 acid, 



Lead nitrate, 



Cobalt acetate, 



Uranium acetate, 



Potassium bichromate, 



Ferric acetate, 



Mangrove-tannin. 



Red deposit on cooling. 

 Yellow ppt. 



1 



! Dirty-green ppt. 



1 Purple ppt. 



1 



I No ppt. 



I No ppt. 



r Pink ppt. 



t Red on surface. 



Deep-red color. 



No ppt. 



Faint cloudiness. 



Red-brown color and ppt. 



Brown ppt. 



Olive-green color and ppt. 



Gallo-tannic Acid. 



No change. 

 No ppt. 



Blue-black ppt. 

 Purple ppt. 



White ppt. 

 White ppt. 



( White ppt. 

 \ Turning blue. 



Yellow color. 

 White ppt. 

 Flesh-colored ppt. 

 Crimson color. 

 Brown ppt. 

 Blue-black ppt. 



These reactions agree closely with those given by Procter 

 for the tannin of Mimosa or wattle bark. 



A further examination of the above mangrove-tannin failed 

 to reveal the presence of sugar. This was accomplished by 

 precipitating a solution of 0.5 gramme of the tannin with lead 

 oxyacetate, removing the lead from the filtrate by hydrogen 

 sulphide, and, after removal of the latter, testing with Feh- 

 ling's solution. 



The Action of Heat. — By heating another portion of the 

 tannin in glycerin to 21 5 , shaking out the products of de- 



1 Text-book of Tanning, p. 113. 



