PHILIPPINE FIREWOOD. 3 



In order to make the following work available in connection with the 

 tanbark industry, which is just in its infancy in these Islands, the wood 

 and bark have in all cases been separated. The wood was sampled by 

 collecting the sawdust from several crosscuts with a sharp saw. The bark 

 was sampled first by breaking it into small pieces and quartering down 

 to a few hundred grams, this was then ground and mixed until homo- 

 geneous. All of the work was done on air-dried samples. As oven-dried 

 wood is very hygroscopic it was thought that perhaps equilibrium would 

 be reached sooner and an air-dried sample more quickly prepared by first 

 drying at 105° and then exposing to the laboratory air. In order to 

 settle this point and the more accurately to define what "air-dried" might 

 mean in the Philippines, the following experiments were carried on : 



Three samples of wood (1) Rhizopliora mucronata Lam. (bacauan) 

 from the trunk of a tree about 30 centimeters in circumference, (2) 

 Brugwiera. gymnorrhiza Lam. (pototan) from Lamao, Bataan, from 

 the trunlc of a tree about 40 centimeters in circumference, and (3) 

 Psidium guajava L. (guava or guayabas), an introduced species, from 

 a limb 30 centimeters in circumference taken from a tree near Manila, 

 contained an amount of water eqiial to 22.8, 21.9 and about 18 per cent 

 of the weight of the wood, respectively. Each sample was dried at 105°, 

 all were simultaneously spread on a flat surface and exposed under iden- 

 tical laboratory conditions. They were analyzed from time to time with 

 the following results : 



Table I. 



Time 

 exposed. 



Moisture. 



Bacauan. 



Pototan. 



Guava. 



Days. 



Percent. 



Pereeiit. 



Per cent. 



















3 



11.73 



11.54 



11.55 



6 



11.74 



11.91 



12.42 



9 



12.73 



12.55 



13.12 



Equilibrium was practically complete after three days, the fluctuations 

 which followed being due foi- the greater part to variable humidity. 



To ascertain whether or not the same equilibrium would be obtained 

 by exposure to air, on the one hand of sawdust containing the original 

 moisture of the gi-een stick and on the other of a dried sample, 

 the following experiment performed imder identical conditions was 

 carried on. 



