﻿PROXIMATE ANALYSIS OF COALS. 



59 



The results with Negros coal Xo. 23 when analyzed by the official method are 

 as follows : 



Table 8. 



Grams 

 water 

 added 

 per gram 

 of eoal. 



Total 

 volatile 

 matter, 

 per cent. 



Ash, 

 per cent. 



Average. 



Total 

 volatile 

 matter, 

 per cent. 



Ash. 

 per cent. 



0.00 



0.1 

 0.2 

 0.3 



71.73 

 70.00 



54. 13 



52.53 



53.62 



9.67 

 10. 22 



13. 28 



14.28 



14.19 



70.86 



54.13 

 52. 53 

 53.62 



9.99 



13. 28 

 14.28 



14.19 



The cause of variation in these averages when the amount of water is 

 changed can be resolved into two opposing factors. First, the water 

 serves to dampen and hold together the solid particles, thereby preventing 

 mechanical loss. The percentage of ash after the first addition of water 

 increases until, with the addition of about 20 per cent, the value is 

 very close to that obtained by the smoking-off process. Secondly, the 

 water exerts an influence on the decomposition of the coals tending 

 to increase the percentage of volatile matter. Tables 6 and 7 show that 

 as water is added, the apparent total amount of volatile matter rapidly 

 diminishes until mechanical losses, as shown by the fact that the percent- 

 age of ash agrees with that obtained by the smoking-off process, are 

 overcome. On the further addition of water the percentage of volatile 

 matter does not remain constant, as would be the case if the dampening 

 effect were the only factor, but it increases while the percentage of ash 

 does not change. In the beginning and until about 20 per cent of water 

 has been added, the first factor predominates; after this the second is 

 made evident. In order further to show the extent of the action of water, 

 experiments were made with two coals as follows : 



Table 9. — Analyses of coals. 



No. 



Source of the coal. 



Official method. 



Smoking- 

 off 

 method. 



Total 

 volatile 

 matter, 

 percent. 



Fixed 

 carbon, 

 percent. 



Ash, per 

 cent. 



Ash, per 

 cent. 



24 



1 



Polillo 



48.53 

 38.63 



44.92 

 48.98 



S.99 

 12.39 



6.00 

 12.54 



Australia 





