58 



WILLIAMS. 



washed with 50 cubic centimeters of water at the temperature of extraction. 

 The solutions were made up to 250 cubic centimeters and analyzed. Color com- 

 parisons were made in Xessler cylinders with dilute solutions and calculated to 

 a uniform tannin content. 



Table IX.- — Extraction of bark of Rhizophora coujugata Linn, at various 



temperatures. 



No. 



Temper- 

 ature. 



Tannins extracted. 



Color, per 



cent of 

 maximum. 



Per cent of 

 maximum. 



Per cent 

 of total. 



1 



o 



30 



60 



80 



Boiling. 



89.0 

 100.0 

 88.8 

 75.2 



74.1 

 83.0 

 73.8 

 62.8 



70 

 75 



90 

 100 



2 ... . 



3 



4 





Table X. — Extraction of Bruguiera eriopetala W. d- A. at variovs temperatures. 



No. 



Temper- 

 ature. 



Tannins extracted. 



Color, per 



cent of 

 maximum. 



Per cent of 

 Maximum. 



Per cent 

 of total. 



1 _ 



o 



30 



60 



80 



Boiling. 



95.5 



96.6 



96.1 



100.0 



72.1 

 73.0 

 72.7 

 75.5 



97.0 



97.0 



98.0 



100.0 



2 - „ — . _ -. 



3 - 



4 - . - 





The results show that pototan (Table X) is little affected by the 

 temperature, while bacauan (Table IX) is best treated at 60°. 



A large number of expedients were tried for clarification of the liquors. 

 Moderately concentrated liquors upon cooling deposit a considerable part 

 of the resinous "insoluble" substances within a few hours. Xeither clay 

 nor alumina increase the amount of "reds" precipitated nor hasten the 

 subsidence. They do cause small losses of tannin. Animal charcoal is 

 worthless. A dilute solution of albumen aids the clarification slightly, 

 but causes some loss of tannin. Nothing as practical as simple cooling 

 and subsidence has been found. 



Suggestions and patent processes for dissolving the "reds" and bleach- 

 ing tan liquors are very numerous. The problem presents many diflB- 

 culties both because of the great ease with which tannins are precipitated 

 or otheiTvise destroj'ed by ver}^ many chemical reagents and because of 

 the intimate relation existing between the bodies which are to be sepa- 

 rated. 



Sulphurous acid was the first reagent tested by myself. Although, of 

 some value in treating certain extracts, it is worthless for that of man- 

 grove. Xeither at high nor low temperatures or pressures does it pro- 



