14 cox. 
It is a difficult task, not yet accomplished, to construct a 
grate that is suitable under any and all conditions of operation. 
Various grates, other than the ordinary bar, have been sug- 
gested and tried on coals of the subbituminous variety to prevent 
the loss of fine coal. I have tried a perforated grate without 
complete success. Mr. A. U. Betts has tried a herring-bone 
grate which he reports to be very successful. The advantage 
of a grate of this type over the ordinary gridiron is that shorter, 
thinner, and more bars may be used without danger of their 
softening and bending, and in this way the air spaces are in- 
creased in number, but diminished in size, without changing 
the ratio between air space and grate surface. It has been 
suggested, also, that the loss of combustible matter in the ash 
could be prevented by burning these coals on a rocking grate. 
It is hoped that the study of the behavior of Philippine coal 
and coals of this class will soon result in the discovery of a 
more satisfactory grate and a method of combustion that will 
be more economical of coal. 
Those Philippine coals which are not wholly satisfactory a 
priori as steaming coals are generally reported to burn exceed- 
ingly well when mixed with a certain proportion of Australian 
coal. I have tried this process with coal from Alcala, Cagayan, 
which analyzed as follows: 
Constituent. Per cent. 
Water 19.3 
Volatile combustible matter 38.8 
Fixed carbon 30.3 
Ash 11.6 
100.0 
Calorific value in calories 4,275 
While the quantity available was not sufficient to enable me 
to record any accurate data, the results were satisfactory and 
I believe the full fuel value of the coal was obtained. Within 
the last few months, the Bureau of Science has tested 20 tons 
of coal from the eastern end of Batan Island. The coal was 
received during heavy rains and was very wet. Its analysis 
was as follows: - 
Constituent. Per cent. 
Moisture 21.7 
Volatile combustible matter 34.9 
Fixed carbon 37.4 
Ash 6.0 
100.0 
Calorific value in calories 4,609 
