24 ON THE HEAT EVOLVED 



may be done. The intrinsic value of the different kinds o* 

 fuel, and the loss or gain experienced by the different construc- 

 tions of the apparatus used for their combustion, are distinct 

 subjects of inquiry, and although both are necessary to be 

 known, to effect any valuable improvement in the selection of 

 the one and the construction of\he other, yet it does not follow 

 as a consequence, because the construction of a grate used 

 for the combustion of Lehigh coal, is more economical than an 

 open fire-place, that, therefore, one ton of the coal possesses 

 greater intrinsic value than one cord of shell-bark hickory 

 wood, as it would be equally relevant, to say, that the coal i» 

 intrinsically of less value, because the wood may be consumed 

 in a sheet iron stove, which is a much more economical appa- 

 ratus than the grate. 



We will resume the subject by comparing one ton of Lehigh 

 coal, at seven dollars, with one hundred bushels of Newcastle 

 coal, at thirty-five dollars, which are the present prices in this 

 market. As 99 : 700 :: 198 : 1400, from which, it appears 

 that fifty bushels of this coal are precisely equal in value to 

 one ton of Lehigh coal, but as the Newcastle coal will cost 

 seventeen dollars and fifty cents, and the Lehigh coal costs 

 only seven dollars, the latter is the cheaper article of fuel by 

 1 50 per cent. 



If the value of a chaldron or bushel of the bituminous coal 

 is required, the manner of obtaining a solution of either ques- 

 tion, is obvious. 



It will be apparent, that although shell-bark hickory has 

 been taken, for convenience, as the standard, to construct the 

 column of comparative values, the economist should take the 

 cheapest article of fuel in the market, as his standard of com- 

 parison. 



The experiments on the Lehigh, Schuylkill, Susquehanna, 

 and Lackawaxen coals were repeated a number of times in dif- 

 ferent quantities, but the results were found to be uniformly 

 the same. Considerable difference was found in the results of 

 pine charcoal, when taken promiscuously from different parcels 

 as brought to market, in consequence of the imperfect manner 



