470 ANNUAL REPORT OF THE OfiF. Doc. 



A study of the chemical analyses of Standard steam coal seems 

 to indicate that the best results have been obtained wherein the per- 

 centages ranged as follows: 



Fixed carbon, 67 to 74 per cent. 



Volatile combustible matter, 17 to 22 per cent. 



Sulphur, 0.5 to 0.9 per cent. 



Ash, 5.0 to 8.0 per cent. 



Gas Coal 



The requisites of a good coal for the manufacture of illuminating 

 gas are: 



(1) That the percentage of volatile matter should exceed 33 per 

 cent. 



(2) That the percentage of sulphur should be low and never exceed 

 0.8 per cent. 



(3) A low percentage of ash, not more than 6 per cent. 



(4) That it should yield from 75 to 85 candle feet per pound 

 carbonized. 



(5) That it should leave, after the extraction of the volatile matter, 

 a bright merchantable coke. 



(6) It should be able to bear transportatioon to great distances, 

 without being reduced to slack. 



An average of six (6) analyses of coals from the Youghiogheny- 

 Westmoreland gas coal district shows: 



Moisture, 1.475 



Volatile matter, 37.404 



Fixed carbon, 56.024 



Sulphur, 0.687 



Ash, 4.410 



Total, 100.000 



Coking Coal 



The essentials of a good coking coal are: 



(1) It should be pure bituminous coal. 



(2) That it should contain a sufficient amount of volatile combus- 

 tible matter (25 to 30 per cent.) to complete the coking pro- 

 cess, with the expenditure of but little, if any, of its fixed 

 carbon. 



(3) It should not contain over 0.7 per cent, sulphur. 



(4) That its phosphorus content should not exceed 0.12 per cent. 



(5) ''That the coke produced from the coal should possess sufficient 

 tenacity to sustain, without crumbling, the burden and blast 

 of the furnace, and the cellular structure should be sufficient- 

 ly open to facilitate its impregnation and solution by the car- 

 bonic acid gas in the furnace." 



