CALORIFIC VALUE OF PHILIPPINE COALS. 173 



was used in my tests. This apparatus is generally accepted as being the most 

 accurate.' While accurate, it is nevertheless expensive and requires an elaborate 

 equipment and a skill in manipulation which prevents as wide a usage as it 

 deserves. A great many attempts liave been made to find a substitute for this 

 apparatus as is shown by the references given at the end of this paper; however, 

 few of these other types give the calorific value more accurately than the result 

 as calculated from easily obtained data. When the necessary apparatus for the 

 direct determination of the heating power is not at hand, it is an important 

 feature to have some means of approximately estimating the calorific value and 

 it is one object of this paper to indicate a method for the calculation of this 

 value for Philippine coal from the results of the proximate analysis. It is 

 hoped that this calculation will fulfill the essential requirements for commercial 

 purposes. 



Owing to the recent revival of interest in Philippine coal, we now 

 make many more analyses than formerly. It is not always convenient 

 to ixadertake calorific determinations of all of these, but I have direct 

 data in sufficient quantity to correlate a formula which will give a result 

 approximately equal to that obtained with the calorimeter. 



Many attempts have been made to develop a reliable formula for calculating 

 the heating power from analytical data. That first proposed was by Dulong for 

 the calculation of the heat of combustion from the results of ultimate analysis, 

 and- is as follows : 



Calorific power=-irr8080C+34500(H — ^) 1 



Others who have contributed to the development of this line of work by 

 furnishing data, suggesting formulse or modifications of that given above are 

 Gmelin, v. Jiiptner, Cornut, Ser, Kern," Seheurer-Ivestner, Meunier-DoUfus, 

 Mahler, Bunte, etc. The calorific work done by Seheurer-Kestner and Meunier- 



8 coutimiea The results obtained by this formula agree very well with those from 

 the empirical formula, which is a correction in calories of two-thirds of the dif- 

 ference between the highest temperature and that of the room, multiplied by 

 four times the duration of the combustion in minutes ; this correction was used 

 in some cases. Th"e' temperature difi'erence was determined by the use of a 

 Beekmann thermometer. 



Detailed directions for the manipulation of a bomb calorimeter in heat 

 determinations, for the determination of the water value of the apparatus, the 

 calculation of the results, etc., may be found, in the publications of Stohman, F., 

 Heber, CI., and Langbein, H. Journ. f. prakt. Ghem. (1889), N. F. 39, 503; 

 Atwood, W. 0. and Snell, J. F. Journ. Am. Ghem. Soc. (1903), 25, 659, and also 

 in many text-books. 



"Braume, J. S. S., and Cowan, W. A. Journ. Soc. Ghem. Ind. (1903), 22, 

 1232 and Gray, Tho. and Robertson, J. G. Ibid. (1904), 23, 704 have made 

 comparative studies of different types of calorimeters and agree that reliable 

 results can be obtained only with some form of bomb calorimeter. 



'" Liebig's process for the estimation of carbon and hydrogen in coals is 

 discussed and the calorific value is calculated by use of the formula 8080C+ 

 34, 460H. Kern, S. Ghem. News (1876), 34, 233. 



