1F254, 255J lignite determination op ash — pyrites. 157 



254, [lis in the cracks and fissures corresponding to this horizontal cleav- 

 tge that we may general^ observe best whether or not any unusual amount 

 b or pyrites is present. We often find the beds subdivided into several 

 . by bands of clay or .-and. and the same is often the case with the minor 

 3ub-divisions, or the plates into which, when rapidly dried, lignite will generally 

 cleave. Of course the amount of ash may thus he increased to such an extent 

 render the material, such as it would lie when obtained on the large scale, 

 infit to serve as fuel. It i- not always, however, that the admixture of an 

 sxcess of mineral matter can be perceived by the eye : it may rise to 50 per 

 id more, and tin- substance .-till retain the aspect of lignite ; though gen- 

 erally, in such eases, it is less (inn. and gradually passes, through many grada- 

 •lt lignitic shale, or lignitic clay. These can, of course, be readily 

 hguished from true lignite by trial in the fire, where lignite, available as 

 fuel, ought not to leave more than 30 per cent of ashes at most — not sufficient 

 to allow ol the form of the fragments being preserved after combustion. Few 



"ignites used on the lai - scale I tin I •- than 2 per cent, of ash ; from five 



to twelve per cent, is, perhaps, the most usual amount. I have thus far exam- 

 ined but fc\v specimens of Mississippi lignite in this respect ; the determinations 

 ry variable, here as elsewhere : 

 1. Compact, massy lignite, from Mr. Moses Bridges, S. •".•'). T. 18, R. 10 E, 

 .v. county. Black, fracture conchoidal, lustrous. Ash greenish yellow 

 light. 



-. Lignite from I Branch, S. 8, T. 10. R. 1' W.. Lafayette county. 



Brownish black: fracture earthy, cleavage slaty. Ash grayish white. 



3. Same as above, from a locality a feu - hundred yards distant. Ash gray- 

 sh white. 



L Lignite from Mr. Vineyards, S. 10, T. 10, I! 1 \\\. Lafayette county, 

 frayish black, fracture earthy, with some shining layers of pitch-coal ; cleavage 

 slaty. Ashes faint reddish yellow. 



5. Lignite from Spears' Cut on the X. E. d- S. W. Alabama R. R., cast of 

 .Marion, Lauderdale county. Black, shining; fracture conchoidal, cleavage 

 laminated. Smells strongly of sulphur in burning: ashes reddish brown, 

 heavv . 



AM01 V.SHES IS t.I'.Nl ! B. 



Ash. 



1. Wfoses Bridges, Choctaw county — (^265). 4.38 per cent. 



1. Hughes' Branch. Lafayette county — (1*263), — i.. 22.29 " 

 ■".. " " " " " ii.. 16.22 



1. Mr. Vineyards, " (T'"263) 21.20 



5. Spear's Cut, Lauderdale county .... (^179) 17.28 " 



255. As to iron pyrites, its presence, to any great extent, is a serious draw- 

 back in several respects. It causes the coal, when exposed to the atmosphere, 

 to exfoliate and crumble, on account of the transformation of the pyrites into 

 copperas ; in burning' it causes it to exhale offensive sulphureous fumes (sulphu- 

 acid), at the same time attacking the grate or furnace to a much greater 

 extent than would be the case with a coal free from this substance ; finally, it 

 the weight of the material and of the ash. — Generally it is not 

 difficult to recognize the presence of this material. It often appears in flattened 

 lumps resembling cast metal, of colors varying from gulden yellow to the pale 

 tint of Britannia ware, on the cleavage planes of the coal; or diffused through 

 its mass, in small rounded particles, i crystals, of the tints above men- 



imes, the mass of the coal may be comparatively free from pyrites, 

 even the latter may be present in plates or layers in some particular 



portion of the stratum, easily separated from the rest ; at others, the mass may 

 be full of minute particles of the mineral, invisible to the eye. In any c;ise, it 

 is easy to determine the point by binning' a sample of the lignite, when not 

 only the slinging sulphureous odor of the smoke, but also the red tint of the ash. 



