COMPARATIVE ANALYSIS 



CUMBERLAND, FORMOSA, AND JAPAN COAL. 



United States Naval Laboratory, 



New York, March 1, 1856. 



In a technical analysis of coal for practical purposes, it is desirable to have a standard of 

 comparison for the value of the coal analysed ; and an analysis of the standard coal selected 

 precedes that of the coal to he judged by it. 



The standard adopted in this analysis is the Cumberland coal used at the navy yard of this 

 station. It is the coal of the Cumberland Coal and Iron Company, and comes exclusively from 

 what is known as " the fourteen-foot or big vein." The specific gravity of this coal is deter- 

 mined from an average of sixty fragments from various parts of a large pile ; and the powder 

 for analysis was obtained by taking portions from many parts of the pile with a shovel, and 

 therefore represents the coal as it is used, and not as it might be selected. 



This coal is black, with smooth shiny surfaces. The fracture is crystalline, with plane 

 cleavage surfaces, well defined angles and edges, and the fragments are cuboid. It is easily 

 broken down into a soft, smooth powder, free from grittiness, of a jet-black color, soiling and 

 adhering to surfaces with which it is brought in contact. This powder, after having been freed 

 by exposure at ordinary temperatures, is peculiar in the property that it gains in weight on 

 being dried at 280°, probably by the oxidation of some of its constituents. The streak left upon 

 drawing this coal over white paper is of a clear umber-brown color, with sharp well-defined edges. 



The Formosa coal is of a more dingy brownish-black color, with smooth tarnished surfaces. 

 The fracture is somewhat laminated, with plane cleavage surfaces, well-defined angles and edges, 

 and the fragments are rhomboid. It is much harder than the Cumberland coal, freer from dust, 

 and much less easily rubbed into powder. The powder is of a brown tinge, but black in color, 

 is rough and gritty, heavy, not dusty, and does not soil or adhere to surfaces like that of the 

 Cumberland coal. The streak is paler, of a dirty fawn color, and somewhat less defined at the 

 edges. Some fragments of this coal are altogether dull in appearance, very friable, and of a 

 fibrous or striated texture and fracture. 



Upon a casual inspection of the Japan coal, of the several parcels, two varieties of it were 

 distinctly noticed. These were found to differ so widely as to require separate analyses. 



The first variety of the Japan coal has the appearance of a mined mineral, and is of a deep 

 claret or purplish-brown color. The lumps are amorphous, and the fracture irregular, altogether 

 dull and unlike that of coal. It is harder than the Cumberland coal, but softer than the For- 

 mosa, and rubs down into a smooth powder, of a dark snuff-brown color and purplish tinge. 

 It adheres to and soils surfaces slightly. The streak is of a yellowish-brown color, less dingy, 

 and better defined than that of the Formosa. 



This variety has a small admixture of heavy lumps of mineral that gives sparks with steel, 

 and is not coal. 



