_Value at _Value at point of mine 1915_ _Quantity_ production, 1915_ ------------------------------------------------------------------------- 1 ton (2,000 pounds) |(1,500 pounds smokeless fuel $5.00[2] bituminous coal |(10,000 cubic feet gas, at contains $1.13 | 90c. per 1,000 9.00[3] |(22 pounds ammonium sulphate at 2.8c. .61 |(2-1/2 gallons benzol, at 30c. .75[4] |(9 gallons tar, at 2.6c. .23[4] Total $1.13[5]| $15.59 ------------------------------------------------------------------------- 1: Gilbert, Chester G., and Pogue, Joseph E., The energy resources of the United States--A field for reconstruction: _Bull. 102, U. S. National Museum_, vol. 1, 1919, p. 11. 2: Figure based upon approximate selling price of anthracite. 3: Figure based upon average price of city gas. 4: These figures would be much higher if an adequate coal products industry were in existence. 5: This figure shows clearly that lowering the cost of production cannot be expected to lower the price of coal. Even if the cost of production were eliminated, the price of coal would merely be a dollar less. =Classification of coals.= The accurate naming and classification of different varieties of coal is not an easy matter. The three main classes,--anthracite, bituminous, and lignite,--have group characteristics determined by their composition, color, texture, origin, and uses, and for general purposes these names have reasonably definite significance. However, there is complete gradation in coal materials from peat through lignite to bituminous and anthracite coals; many varieties fall near the border lines of the main groups, and their specific naming then becomes difficult. In addition, coal is made up of several substances which vary unequally in their proportions. It is difficult to arrange all of these variables in a graded series in such a fashion as to permit of precise naming of the coal. Furthermore, the scientific naming of a coal may not serve the purpose of discriminating coals used for different commercial purposes. Even the commercial names vary among themselves, depending on the use for which the coal is being considered.