1,332.372 S.T. 



1.643.832 S.T. 



5 1.934. 



H 2.924.427 S.T. 



132 The National Geographic Magazine 



I 5 i.2oo.t84 sHORiTONs bv which thc cokiiig properties of a coal 



are determined. The value of a coking 



coal lies largely in the fact that coke is 



g 1,473.211 S.T. practically the only fuel that can be used 



to advantage in the production of iron. 

 For this use the coke has to be of excep- 

 tional purit}^, containing an especially 

 low percentage of sulphur. It also must 

 have a well-developed cellular structure 

 I 2,664.926 S.T. aud bc stroHg enough to withstand the 



pressure of the modern blast furnace. 



Most of the coke of this character is pro- 



3.983. 37B S.T. duccd iti thc Appalachian coal field in 



.. ,,= ,,. . - Pennsylvania, West Virginia, Virginia, 



Tennessee, and Alabama. In general the 

 coke from the western fields is inferior to 

 that from the east, and little of it can be 

 used in the manufacture of pig-iron. 

 Most of the coke manufactured in the 

 west is used by the smelters where a 

 lower grade of fuel will suffice. 



As shown on the map on page 135, 

 the various coal fields of the United 

 States are cut unequally by the boundary 

 lines of the different states, but, since 

 statistics are always given by states, they 

 will be regarded as the units. 



The coal production of the various 

 states, yielding over one million short 



37.7©I.S00 S.T. 



38.434.363 S.T. 



. 637 SHORTTONS 



Coal Output of Principal Coal Producing States 



distinctions which are of great impor- tons of coal in 1905, is shown in the 



tance ; thus the property of coking, which accompanying diagram, 

 is limited entirely to the bituminous class, 



has given to coals possessing this pecu- Pennsylvania produces the most coal, 



liarity a value far above those coals hav- ^"T Montana has the largest 



ing similar composition, but which do '^°"'^^ Fields 



not possess this characteristic. The rea- As commonly understood, Pennsyl- 



son why one coal will coke and another vania heads the list with a production 



will not is not understood ; apparently it which dwarfs that of all other states into 



does not depend upon chemical compo- insignificance. The other states of the 



sition, but rather upon some physical east that occup_v prominent positions are 



property which no one has been able to Illinois, West Virginia, Ohio, Indiana, 



define. A practical test is the only way and Alabama. Of the western states. 



