﻿46 cox. 



By the transition method: 



Moisture 



(15.42) 



(15.42) 



(15.42) 



Volatile combustible matter 



40.50 



40.26 



40.38 



'y the smoking-off process: 









Moisture 



(15.42) 



(15.42) 



(15.42) 



Volatile combustible matter 



39.12 



39.46 



39.45 



Fixed carbon 



41.35 



41.00 



■ 41.02 



Ash 



4.11 



4.12 



(4.11) 



100.00 100.00 100.00 



Iii choosing the nest sample with which to experiment, one very 

 high in impurity was selected, so that extremely small mechanical losses 

 could be noted by a variation in the percentage of ash. This, an air-dried 

 coal from Negros, No. 21, gave the following results : 



By 



the official method: 





Per 



cent. 







Moisture 



18.19 



18.29 



(18.24) 



(18.24) 





Volatile combustible matter 



38.73 



39.13 



40.45 



41.91 





Fixed carbon 



26.57 



25.90 



25.54 







Ash 



16.51 



16.68 



15.77 







100.00 



100.00 



100.00 





By 



the transition method: 













Moisture 



(18.24) 



(18.24) 



(18.24) 







Volatile combustible matter 



32.56 



32.66 



32.64 







Fixed carbon 



31.39 



31.39 









Ash 



17.81 



17.71 









100.00 



100.00 





By 



the smoking-off process: 













Moisture 



(18.24) 



(18.24) 



(18.24) 



(18.24) 





Volatile combustible matter 



32.03 



31.98 



32.02 



31.97 





Fixed carbon 



31.77 



31.74 









Ash 



17.96 



18.04 







100.00 100.00 



There are a great many factors which influence the amount of volatile 

 matter driven off from a sample of coal, namely the size of the grains, 

 the weight of the sample, the condition of the coal — that is, the quantity 

 of moisture, etc. — and the degree and duration of the heat. Notwith- 

 standing these considerations it is generally conceded that under uniform 

 conditions the same operator has little trouble with duplicates in ordinary 

 coal analysis and I wish to show that in the analyses of Philippine coals 

 this is true when the modification methods are used. Even different 

 operators working under prescribed conditions obtain insignificant varia- 

 tions in results. My records show that on June 21 of this year this 



