OXIDATION AND DETERIORATION OF COAL. 811 
The action of sunlight on coal not only increases its temper- 
ature directly, but also catalytically by accelerating the absorp- 
tion of oxygen, and thus in two ways it increases deterioration 
and the danger from spontaneous combustion. 
A coal which illustrates these points is that now being mined 
on the eastern end of the Island of Batan.1> On exposure to the 
sun and air it alters rapidly, loses its luster, and falls into powder. 
It slakes in shipping, unless it is kept from the sun and wind 
while in transit. Spontaneous combustion has several times 
occurred in this coal, but the particulars are not available, 
except in the more recent cases. The Civil Government of the 
Philippine Islands used some coal from the Batan mine during 
1911 and had trouble with 9,000 tons of the same coal in piles 
about 5 meters high placed on the ground under a roof. The 
piles were ventilated with alternate tiers of horizontal air pas- 
sages, about 6 meters apart and at right angles to each other. 
In this case there was no actual flame, but all of the timber used 
to make the ventilators was badly charred. 
In coal heating in bunkers, even though the temperature be 
only moderately raised, there is an increased escape of volatile 
combustible matter and consequent loss of fuel value. Evidently 
the danger from spontaneous combustion of coal may be reduced 
by assisting in every possible way the dissipation of heat through 
_ radiation by having the coal sufficiently close to air-cooled sur- 
faces,'* but any system which brings the air freely into contact 
with the coal should be avoided. Ventilation of this sort may 
mean danger of fire, because it is very difficult to provide suffi- 
cient radiation to remove the heat as fast as it is formed. 
Storage piles should be protected from the sun and every other 
external source of heat. 
Any method which protects the coal from the air will pre- 
serve it. This can unquestionably be done by submergence in 
water, but this necessitates firing wet coal.” Firing of wet 
coal may be avoided by dry storage in carbon dioxide or other 
inert gas. I believe there will be little danger from fire in 
storage of this sort, for the air supply is cut off. Deterioration 
* This coal is a poorer grade than that from the western end of the 
island. ; 
*The coal should be stored in bunkers which have surfaces large in 
proportion to the bulk, or air might be circulated through the heaps in 
fron pipes in such a way that it does not come in contact with the coal. 
“Parr and Hamilton, Hconom. Geol. (1907), 2, 703, “Submerged coal 
does not lose appreciably in heat value.” See also the bibliography at 
the end of this paper. 
