PHILIPPINE FIREWOOD. 5 



of the wood and assumed 11 per cent as the minimum hydrometric moisture 

 in that climate. 



In the Philippines, where the humidity is high and fairly regular, 

 variation is much less than in countries where the climate is hot or cold, 

 moist or dry, depending on the season. From the above and following 

 results it will be seen that the water content seldom falls below 13.5 or 

 13.0 per cent of the weight of the diy wood, and it may be conjectured 

 from the following, and also from unpublished analyses which I have 

 made, that this may be a good average for thoroughly seasoned firewood. 

 The moisture content of air-dried bark is about 14.5 per cent. 



The moisture determinations in the above experiments as well as in the 

 following ones were made by weighing a sample into a tared platinum crucible, 

 drying in an oven at a temperature of 103° to 105°, after which it was cooled 

 in a desiccator and weiglied. The process was repeated until further drying 

 showed very little loss in weight. 



The ash was determined by carefully burning the organic matter of the 

 wood with free access of air and weighing the residue. A discussion of this 

 process will be found on page 10. 



The dry weight is taken as the basis on which to compute the percent- 

 ages of moisture and of ash. The advantage of computing percentages 

 on this basis is that it furnishes a constant means of comparison, whereas 

 if computed on the actual or wet weight the basis would vary with every 

 change in the amount of moisture. 



The determination of the calorific value of the wood was made in a 

 Berthelot-Mahler bomb calorimeter under a pressure of 20 atmospheres 

 of oxygen. The constants used were those which had been carefully 

 determined for previous work and the corrections for wire fused, etc., 

 were made according to the usual methods.^^ 



The woods investigated are from various sources. Some of them 

 were collected for me by Dr. H. F. Whitford, of the Bureau of Forestry, 

 and by Dr. F. W. Foxworthy, of this Bureau, and the latter has made all 

 of the botanical identifications. These, with such other information as 

 I have at hand, are given below. The common name or the name under 

 which the sample was received is given first, followed by the botanical 

 name in parentheses. 



Sample No. 1. — Agoho ( Casuarina equisetifolia Forst. ) . 

 Sample No. 2. — Guava (Psidium guajava Linn.) an introduced species. 

 Sample No. 3. — Pototan (Bruguiera gym.norrhiza Lam.) from Lamao, Bataan. 

 Sample No. Jf. — Bacauan {Rhizophora mucronata Lam.). Wood from the trunk 

 of a tree about 15 centimeters in diameter. 



Sample No. 5. — Bacao {Rhizophora conjugata Linn.). 



"Cox, A. J., This Journal, Sec. A (1909), 4, 172. 



