354 The Philippine Journal of Science 1915 



gives a green-black precipitate with iron salts, a light brown 

 precipitate with bromine water, and crimson line when in con- 

 tact with one drop of concentrated sulphuric acid. Upon 

 analysis a representative sample of the bark gave the follow- 

 ing results, calculated on water-free material: Total extract, 

 34.77 per cent; nontannin, 9.41 per cent; tannin, 25.36 per cent. 



Camanchile bark infusion soon ferments and decomposes in 

 this climate, resulting in the destruction of tannins, the develop- 

 ment of a disagreeable odor, and a thickening of the liquid due 

 to a viscous gelatinous formation which accumulates and grows 

 on the surface. A few experiments with phenol as a preserv- 

 ative showed that a concentration of 0.01 per cent does not check 

 the fermentation appreciably, as in a control infusion the tannins 

 were destroyed, the color became a deep wine red — at least three 

 times as intense as the original red orange — a somewhat pene- 

 trating smell was given off, and a gelatinous formation and a 

 slimy sediment developed, which made the infusion viscous. 

 After four months the loss of tannin amounted to 15 per cent 

 of the total tannin content. An infusion containing 0.1 per cent 

 phenol at the end of the same period showed a practically unal- 

 tered tannin content and an acidity equal to 0.0714 gram acetic 

 acid per 100 cubic centimeters. A little fermentation which soon 

 ceased had produced some slimy sedimentation, but had not 

 altered the appearance or odor of the clear supernatant infusion. 



Camanchile bark contains irritating principles, which are 

 believed by laborers in the tanneries to indicate roughly the 

 strength of infusions. Infection of the eyes, producing weaken- 

 ing of the sight, and irritation and swelling of the lids are 

 attributed to them. 



Through the cooperation of Dr. Fred W. Foxworthy, of the 

 College of Forestry at Los Banos, who collected and sent me the 

 material, I was enabled to examine several barks and fruits 

 which have not as yet been used as tanning materials. The 

 results are presented in Table VIII. 



Of these tanning materials none seems particularly promising, 

 either on account of the insufficient supply or on account of the 

 low tannin content. 



THE FILIPINO PROCESS OF TANNING 



As has been stated previously, the Filipino process of tanning 

 is very primitive and produces a very inferior grade of leather. 

 It was desired to make a study of this process in order to point 

 out its prime defects and to suggest improvements which might 

 be put into effect without materially increasing the investment 



