ECONOMIC POSSIBILITIES OF MANGROVE SWAMPS. 



47 



He attributes the low results of the Freiburg school to improper packing for 

 shipment. 



Two ' analyses of Rhizophora mucronata Lam. from Zanzibar show 34.3 and 

 35.8 per cent of tannin in barks containing 16.2 and 16.4 per cent moisture, re- 

 spectively. Blockey ' reports some analyses of Indian mangrove barks as follows : 



Bruguiera gymnorrhiza 

 Kandelia rheedii 



Rhizophora mucronata 

 Ceriops candolleana 



Tannin 

 (per cent). 



9.7 



17.3 



I 4.5 



1 6.1 

 18.0 



Various trade notes give the barks of India as averaging 25 to 29 per cent 

 of tannin, which doubtless is more nearly correct. The results of the Freiburg 

 school and those of Blockey certainly do not represent the average barks of 

 the two regions. 



The Philippine Bureau of Forestry has furnished the following report 

 upon four samples of Philippine barks submitted to the Bureau of Plant 

 Industry at Washington. 



No. 15335 B. F. (Ceriops tagal (Perr.) )„ 

 No. 15336 B. F. {Rhizophora eonjugata 



L. ) 



No. 15337 B. F. {Bruguiera eriopetala W. 



& A.) 



No. 15338 B. F. {Bruguiera parviflora W. 



& A. ) 



Total 

 solids. 



Soluble 

 solids. 



58.58 

 53.91 

 37.36 

 24.43 



49.02 

 51.03 

 36.81 

 19.82 



'Reds' 



Non- 

 tannin. 



9.56 

 2.88 

 0.55 

 4.61 



13.19 



11.64 



10.15 



7.27 



Tannin. 



35.83 

 39.39 

 26.66 

 12.55 



E.KPEEIMENTAL. 



The swamp area of the east coast of Sibuguey Bay, Mindanao, from the 

 mouth of the Vitali Eiver to that of the Bulaan, a distance of some 40 

 miles, has been taken as representative in a general way of the better 

 swamps of the Philippines. Different species predominate in different 

 areas and there are of course considerable variations in the stands of 

 timber. However, in the matter of the tannin content of the bark of 

 any given species, no considerable variation is to be expected in Phil- 

 ippine swamps of approximately equal development. 



I have found that this area will yield about 20 metric tons per hec- 

 tare of fresh bark of mature trees of selected species averaging about 

 28 to 30 per cent of tannin on the dry weight. Only four species are 

 included in this estimate, all others being negligible from a commercial 



'Bull. Imp. Inst., London (1904), 2, 16.3-166. 

 ^Journ. Soc. Chem. Ind. (1902), 21, 158. 



