352 cox. 



I have already shown*" that when Philippine coal is rapidly lieated 

 in the ordinai-y laboratory analysis according to the directions recom- 

 mended by the committee appointed by the American Chemical Society,^" 

 there is a very large mechanical loss amply indicated by the shower 

 of incandescent carbon particles which are driven oflE during the first 

 one or two minutes heating. Without the most careful stoking in the 

 furnace there is probably the same rapid expulsion of the volatile matter 

 as in the laboratory method, with a corresponding quantity of fine 

 particles carried mechanically in the gas stream and to a greater or less 

 extent deposited or bui-ned out of the range of the absorption tubes. 

 I have also shown^^ that the presence of water serves to dampen down 

 and hold together the solid particles of a coal, thereby preventing 

 mechanical loss. This is probably where the advantage, if any, comes 

 when an engineer wets a highly volatile coal. 



It has been shown^^ that fuels classified according to the increasing 

 percentage of volatile combustible in their total combustible matter, 

 when burned under a Heine boiler decrease somewhat in efiiciency. 

 While this conclusion holds when the number of samj)les averaged is 

 siifBciently large, one must avoid too wide an application of the general- 

 ization. Often there are physical features and special reasons for choos- 

 ing one coal before another when theoretically it is not so good. In 

 coking and non-coking coals apd in those entirely different physically, for 

 examj)le, slack and briquettes, clinkering and non-clinkering, there are 

 factors which have many times more weight and such a generalization 

 hardly could be applied to these, while such a comparison is perfectly 

 legitimate and helpful to coals of the same class and physical condition. 



It is hoped that as soon as the public realize the availability of reliable 

 information regarding coal, both concerning its composition and steam- 

 ing value, these means of determining its value may be more often 

 resorted to and that guesswork may be eliminated from the purchase of 

 a coal. 



SUMMARY. 



The object of this investigation was to determine the steam-making 

 value of the coals of the Philippine Islands as compared with the foreign 

 coals ofl:ered on the market in this Archipelago. 



All the tests which are described in full were made at the Bureau of 

 Science with a 75-horsepower water-tube Babcock & Wilcox steel boiler 

 over a hand-fired furnace. An average of 111| per cent of the rated 

 capacity and an average steam pressure of 7.4 kilograms per square 



=''Cox, A. J.: This Journal, Sec. A (1907), 2, 43. 



'"J. Am. Chem. Soc. (1S99), 21, 1110. 



" Cox, A. J. : Loc. cit. 59. 



=-'r. S. G. S. Bull. (1907), 325, 89. 



