270 



ANNUAL OF SCIENTIFIC DISCOVERY. 



on their way to the East Indies, and a few years ago an English 

 government steamer was burnt in the Mediterranean by the sponta- 

 neous combustion of its coal. 



In short, for a combination of the highest evaporative power, with 

 the least bulk, facility of ignition, and completeness of combustion, 

 and for the absence of any tendency to clog the furnace, to clinker, 

 or to cake, semi-bituminous coals, for purposes of steam locomotion, 

 must have the preference over the other kinds. 



By far the most elaborate experiments on this subject are those 

 conducted under the direction of the naval department at Washing- 

 ton, by Professor Walter R. Johnson, whose elaborate Report of 

 600 pages lies before us. The results are given in numerous de- 

 tailed tabular statements. And at the end are the tables, in which 

 are exhibited the character and efficiency of the several coals. The 

 examination embraced over forty specimens, including various foreign 

 kinds. From the first of these we take the following figures, in 

 which the coals are compared with reference to bulk and space re- 

 quired for stowage, proportion of carbon and volatile matter, and 

 evaporative power. 



Official Analysis of Anthracite and Bituminous Coal. 



Anthracites. 

 Peach Mountain . 

 Lehigh . 



Forest Improvement 

 Lackavvanna 



Weight per Cubic feet Fixed Bitumen or Earthy 



cubic foot. per ton. carbon, volatile matter, matter. 



. 53.78 41.64 89.00 2.96 6.13 



. 55.32 40.50 89.15 525 5.56 



. 53.06 41.75 90.75 3.07 441 



4889 45.82 87.74 3.91 6.36 



Evap'ive 

 power. 

 !45 

 835 

 940 

 915 



Semi-bituminous 

 Neff's Cumberland 

 Maryland Mining Company 

 Blosburgh . 

 Dauphin and Susquehanna 



Bituminous 

 Newcastle 

 Liverpool 

 Sidney . 

 Pictou . 



Richmond, Virginia 

 Cannelton, Indiana 



5.40 



4.62 



5.49 



12.51 



8.95 



4.97 



809 

 733 

 747 

 792 

 775 

 686 



In the last table the ranks of coals are assigned, according to their 

 practical qualities, in ten different particulars. In respect to com- 

 pleteness of combustion, the second rank is assigned to the Cumber- 

 land coal. And it holds the first rank for evaporative power, under 

 equal weights and equal bulks, and for the evaporative power of its 

 pure combustible matter. For freedom from waste in burning, the 

 soft bituminous coals stand first; but some of the Cumberland speci- 

 mens stand very high, as high as the eleventh of forty-four kinds. 

 And for maximum evaporative power, under given bulks, coal from 

 Cumberland stands first. 



At the close of his Report, Mr. Johnson truly remarks, that it is 

 not " easy to assign the exact relative weight or importance of the 

 several qualities indicated. In steam navigation, bulk as well as 

 weight demands attention ; and a difference of twenly per cent., 

 which experiment shows to exist between the highest and the lowest 



