﻿PROXIMATE ANALYSIS OF COALS. 



55 



Leading cmt of consideration those coals in which there is a discordance 

 in the percentage of ash as determined by the two methods, we can draw 

 some conclusions from the analyses. 



By a selection there are fourteen samples which show no or only very 

 slight mechanical losses when analyzed by the official method. In these 

 the deviation in the percentage of volatile combustible matter and there- 

 fore of fixed carbon is due entirely to the difference in the breaking down 

 of the volatile constituents of the coal. When arranged in the order of 

 the decreasing variation of the percentage of fixed carbon as determined 

 by the official method and the smoking-off process they fall into two 

 groups as follows: 



Table 3. 



Number and group. 



Source of coal. 



Differ- 

 ence in 

 per cent. 



Group I: 



26 



Polillo.. 



4.87 

 4.57 

 4.16 

 4.12 

 3.34 

 3.05 

 2.65 

 2.33 

 2.25 



2.00 

 1.97 

 1.55 

 1.45 

 1.34 



3 — 



Australia _ 



37 



Zamboanga .. 



8 



Batan Island .. .. 



24 _ _ ... .. 



Polillo. . ... 



12 . 



Cebu 



2 





1 _ . . 



do 



27„ ... 



Polillo. . . 



Group II: 



i . 



Batan Island 11 



31 . . 



Samar _. .. 



.do.. 



32 _. _ .. 



28 ..... 



Philippines 



34 



Tayabas . 





The difference in the amount of fixed carbon depends both on the 

 amount of the volatile ingredients in the coal and on the nature of these 

 volatile compounds. The first factor is approximately the same in Phil- 

 ippine coals, 12 and therefore the cause of the variation is to be sought in 

 the nature of the volatile compounds. We well know that volatile in- 

 gredients of similar composition may differ to a considerable extent in 

 volatility and afford entirely different products on destructive distillation 

 and that it is impossible chemically to formulate this change; never- 

 theless, judging from the analyses of some of the gases we should expect 

 the difference in the breaking down of the volatile ingredients under 

 the different heat treatments of the two methods to be about as it is. 

 The more complex the volatile matter, the greater the disparity to he 



11 This was taken from the southeastern end of the. island. It is a well- 

 known fact that the coals from this region are of a much poorer grade than those 

 from the western end where the military reservation claims are located. e 



12 Cox, A. J.: Log. cit. 



