EDITORIAL. 



THE RELATIONSHIP BETWEEN THE EXTERNAL APPEARANCE 

 AND THE ASH CONTENT OF PHILIPPINE COAL. 



A qiiantity of coal from a mine south of Sydney, Australia, was sent to 

 this Bureau in 1907 for test. The coal was fairly comjiact and for the 

 most part with a hackly fracture. It was markedly characterized by al- 

 ternating dull and lustrous bands parallel to the bedding planes. The 

 lustrous bands were usually not over a few millimeters in thickness, while 

 the dull layers were many times that. The lustei of the lustrous bands 

 was quite brilliant, apfiroaehing the vitreous appearance of obsidian. It 

 occurred to me that the difference in the brilliance of the bands might be 

 due to the content of earthy matter. The two were carefully isolated 

 and the ash determined as follows : 



DuU portion 



Lustrous portion 



(percent). 



(percent). 



12.1 



2.6 



These numbers show that without douljt a large part of the difference 

 in luster is due to the ash content. 



I do not think that coals from entirely different sources are to be 

 compared, but it is quite probable that the luster of coal from the same 

 vein or same field may vary inversely as the content of earthy matter. 



I have already called attention^ to the striking similarity between all the 

 coals thus far discovered in the Philippine Islands, and I have arranged 

 the record of a number of samples of these together with some from 

 Aiistralia in the order of their descreasing ash content, in the following 

 table : 



Philippine coals arranged in order of decrease in ash content. 



Source of coal. 



Ash 



(per 



cent). 



Luster of the coa). 



Tayabas, Mauban __ 

 Negros, near Cadiz _ 



Batan Island 



Negros 



Australia 



Australia » 



Australia 



Negros, Escalante _ 

 Surigao 



31.50 

 18.00 

 14.70 

 14.23 

 12.55 

 12.01 

 9.99 



9.55 

 9.06 



Very dull. 



Dull to sublustrous. 



Dull, 



DuU to very lustrous, uneven. 



Dull to lustrous, uneven. 



Dull. 



Dull for the most part. Streak 



very lustrous. 

 Sublustrous to lustrous. 

 Sublustrous, uneven. 



" Given above. 



"■The Mineral Eesources of the Philippine Islands, Bulletin of the Division of 

 Mines, Bureau of Science, Manila, 1008. 



91 



