CALORIFIC VALI'E OF PHILIPPINE COALS. 181 



This chart has heen drawn on the basis of the Goiital formula with 

 my values for "a" given on page IT 9, and from it the approximate 

 calorifie value of the coal may be found, when the proximate analysis 

 as made by the official method is known. The procedure is as follows: 



Find from the analysis the percentage of volatile combustible matter in the 



pure coal | ^ m _l r p I " Locate this value on the chart and follow the 



ordinate (vertical line), until it intersects the curve representing the volatile 

 combustible matter which agrees with the percentage determined in the analysis ; 

 continue from this point along the abscissa (horizontal line), until the curve 

 representing the percentage of fixed carbon of the analysis is reached; continue 

 doivnward on the ordinate to the base line where the calorifie value of the coal 

 may be directly read. Example: 



Analysis of the coal. 





Constituent. 



Per cent. 



Water 



5.75 



Volatile combustible matter 



40.00 



Fixed carbon 



50.00 



Ash 



4.25 



Total 



100.00 



100 V. C. M. 





V. C. M. + P. C. ' '- ^ • 



in the pure coal. Locate 45 on the chart and follow the ordinate 

 as indicated by the arrow until it intersects the curve representing 40 

 per cent of volatile combustible matter; continue from this point along 

 the abscissa until the curve representing 60 per cent of fixed carbon 

 is reached; continue downward on the ordinate to the base line where 

 the calorific value of the coal may be read as 6,630 calories. 



Goutal assumed the calorific value of the fixed carbon of all coal 

 to be 8,300 calories,^" or the share that fixed carbon contributes to 

 the calorific value of coal as eight3'-two times the per cent of fixed 

 carbon in the sample. This was substantiated by the determination of 

 the calorific value given above for an Australian coal, but it does not 



'"Streit, H. Dissert. Univ. Zurich (1906); Chem. Als. (1908), 2, 1040 has 

 shown that the heat of combustion of ash- and moisture-free coke obtained by one 

 and the same method from different coals is the same but differs if different 

 methods are employed. Crucible coke produced by the French (Goutal) method 

 is least degasified, by the American method most; that by the Bochum method 

 occupies an intermediate position. In general the heat of combustion of pure 

 cokes is as follows : 



Crucible coke : Calories. 



Goutal 8,230 



Bochum - 8,160 



American 8,100 



Gas coke : 8,000 



Oven coke 7,950 



