54 



WILLIAMS. 

 Table VIII. — Analyses of hark of Sonneratia pagatpat Blanco. 



Sample No. 



Diam- 

 eter of 

 tree. 



Parts per 100 of water-free 

 material. 



Insol- 

 uble. 



Total 

 extract. 



Non- 

 tannin. 



Tan- 

 nin. 



13 



Cm. 

 50 

 50 

 82 

 20 



82.3 

 80.7 

 80.1 

 81.4 



17.7 

 19.3 

 19.9 

 18.6 



5.6 

 7.3 



7.6 

 7.8 



12.1 

 12.0 

 12.3 

 10.8 



14 



44 



56 - - ------- 





Average 



50.5 



81.1 1 18-9 



7.1 



11.8 











A survev of the data shows that only four species can be depended 

 upon to furnish a supply of bark. They are Rhizophora mucronata, R. 

 conjugata, Bruguiera gymnorrhiza and B. eriopetala, the two former 

 commonly known as "bacauan," the two latter as "pototan" or "pitutan." 

 Tangal, which is the "teiigah" bark of Borneo upon which the manu- 

 facturers there depend to a considerable extent, is scarce on Sibuguey 

 Bay. Both Xylocarpus granatum and X. obovatm yield too small quan- 

 tities of bark per tree to be remunerative. Bruguiera parviffora has a 

 very low tannin content, as has Sonneratia pagatpat. 



However, a use may be found for the last mentioned for blending 

 with the more valuable barks, since it produces a leather of good, brown 

 color, very different from any tanned by barks of the Rliizoplwracece. 

 Some samples of leather were tanned with well-preserved barks by the 

 method suggested by Parker and Procter,^" using goat skin instead of 

 sheep grain, as the latter was not obtainable in Manila. 



No. 



Tanning material. 



Bacauan 



Pototan 



Pagatpat 



Bacauan 



Pototan . }equal parts 



Pagatpat 



Description of leather. 



Dark red, somewhat thick grain. 



Not distinguishable from No. 1. 



Medium brown, porous, soft, smooth grain. 



i Reddish brown, better than either Nos. 1 or 

 2, grain smooth. 



In calculating the yield of bark in the area examined, only bacauan 

 and pototan trees 20 centimeters or more in diameter have been counted. 

 For this purpose seven rectangular areas of about one-fourth hectare each 

 were selected as representative after a fairly thorough exploration of the 

 surrounding swamp. These areas are distributed at approximately reg- 

 ular intervals between the mouths of the Vitali and Buluan Elvers. 



'" Parker, J. C, & Procter, H. E. Numerical expression of color. Journ. Soo. 

 Chem. Ind. (1895). 14, 125. 



