CALORIFIC VALUE OF PHILIPPINE COALS. 197 



highly weathered outcrop samples is about 500 calories. When it is 

 definitely known that a sample is from one of the regions enumerated 

 in Table V, then it would be more accurate to use the average value 

 for "ft" there given, and the discrepancies between the calorimeter and 

 the calculated calories would be greatly reduced. '^^ Such a degree of 

 accuracy gives a good working formula and is as close an agreement 

 as is to be found between many of the calorimeters in actual use to-day. 

 Should future development and deeper boring prove that better coal 

 exists in these Islands and that this formula is no longer applicable, 

 let it be remembered that the data from which this formula is derived 

 are not changed one iota. In a recent publication Constam and Eou- 

 geot ^"^ conclude that a variation for the same coal of over three per cent 

 may be expected. . They used a Parr calorimeter, which is in wide 

 use in America for this work. Lunge and Grossmann ^'' discuss the 

 paper of Constam and Eougeot and state that an apparatus which varies 

 100 calories is sufficiently accurate for technical purposes. The results 

 of my formula do not greatly exceed these limits and are fairly satis- 

 factory when we consider that two independent samples of the same 

 coal show as great variation as this. 



The heating value of the upper bed Philippine coals may be easily 

 determined by the chart given in fig. 3, when the results of the proximate 

 analyses are known. The intersection of that ordinate, which corresponds 

 to the proper percentage of fixed carbon (respectively volatile com- 

 bustible matter) in the total combustible matter read on the abscissa, 

 with the curve representing the percentage of water and ash in the coal, 

 designates the abscissa which in turn indicates the calorific value given 

 on the ordinate. 



Authors ^* sometimes recommend corrections or modifications of the 

 present analytical methods used in the determination of the composition 

 of coal,- such as that the chemical tests be limited to the determination 

 of the ash and the heating power of the pure coal, abandoning in the 

 future the determination of the moisture, volatile matter, fixed carbon, 

 sulphur and evaporating power of the coal.'" These, when sifted down 



'^ The physical and chemical properties, the character, the water content 

 (Kohr, O. Ghem. Ztg. (1908), 32, 580, Cothen) and the color of the ash (Knappe, 

 C ibid., 657) may be of assistance in verifying the locality from which a coal 

 comes. Such observations are especially valuable on samples purporting to be 

 from well established coal fields. 



""Constam, E. J. and Rougeot, R. Ztschr. f. angew. Ohem. 1906, 19, 1805. 



"Lunge, G. and Grossmann, H. Ibid., 1963. 



^Bement, A. Eng. Record (1906), Oct. 27, 473. 



°° Our present methods for the proximate analysis of coal probably had their 

 origin in the "immediatanalyse" of L. Gruner {Ann. Mines (1873), III, 2, 511; 

 4, 169; Polytech. Journ., (Dingier) (1874), 213, 73.) who believed that the 

 simplest and safest method of ascertaining the real value of a coal was the 

 determination of the water, coke, and ash. 



