298 0).4 
desirable in this paper to discuss the literature of the subject 
in detail, and I shall confine myself chiefly to the results of my 
own experimental work, the study of which I began in 1908. 
I have selected samples of coal for my investigation from some of 
the: best sources in the Philippines. 
Sample No. 1 is a coal from the military reservation, Batan 
Island, several tons of which were shipped in sacks direct from 
the mine to the Bureau of Science for a steaming test. During 
the test, 100 kilograms were collected, a shovelful at a time, and 
from this a small sample was secured by quartering and reducing 
the size of the pieces to that of a small marble. A 2-liter glass- 
stoppered bottle was completely filled from the sample and the 
air excluded. This was reserved for experimental purposes. 
Sample No. 2 is from Polillo and was taken by me from a pile 
of 16 tons which had lain in an open bunker for a year. The 
sample was prepared and kept as described for No. 1. ; 
Sample No. 3 is from Camansi vein No. 2, near Danao, Cebu. 
The coal was shipped in sacks from Cebu soon after being mined 
direct to the Bureau of Science for a steaming test. The sample 
was taken and bottled as described for No. 1. 
Sample No. 4 was brought to the laboratory from Bulalacao, 
Mindoro, in a sack. This coal was sampled as described above. 
Sample No. 5 came from the mountain district of Luzon and 
had been stored in sacks in our warehouse for one and one-half 
years, when it was sampled for these experiments in the same 
manner as the others. 
At the beginning of the experiments, each sample was carefully 
worked over to remove noncoal particles, cracked until all 
pieces would pass a sieve having 2 meshes to the centimeter 
(5 meshes to the inch), and that portion which would pass a 
sieve having 4 meshes to the centimeter (10 meshes to the inch) 
was discarded. It was then looked over again, grain by grain, 
to see that no earthy matter or lint was intermixed. The samples 
were made as uniform as possible. All these operations were car- 
ried on in the air. For each experiment a sample was quartered 
from the bulk sample, so that all results are comparable in this 
respect. All analyses were made according to standard chemical 
methods, and especial care was exercised to maintain uniform 
conditions. In the determinations of the calorific value, the same 
Berthelot-Mahler bomb calorimeter was used throughout and 
the temperature differences were determined by the use of a 
Beckmann thermometer. I have made a water correction of the 
results by subtracting 6 calories for each per cent of water. All 
