170 Miscellaneous. [Feb. 



cross fracture, and in the sunshine, after a shower of rain, it is perfectly- 

 radiant with the bright places, which have often a pavonine lustre, and 

 the abundant laminse of pyrites which are all disposed like them vertically 

 to the horizontal planes. On the horizontal places of the blocks, which 

 are something less than six inches thick, the lustre is a dark velvet black 

 and few or no traces of the pyrites are seen except in minute veins, often 

 forming rhomboids which mark the intersecting edges of some of the 

 larger laminae. In a few instances the vertical plates of pyrites are 

 replaced by plates of calc spar. 



Its specific gravity is 1 .290 



Its analysis gives per cent. 



Hygrometric water, 2.25 



Gaseous and Bituminous matter, 24.50 



Iron and a little silex and lime, , 4.75 



Carbon, 69.00 



100.50 



The excess is from the peroxidation of the iron. 



What was given to me as the damaged coal on board the Sir Howard 

 Douglas was evidently nothing more than the top coal, or coal shales at 

 the top and bottom of the seam, and upon examination this proved to 

 be the case, for it contained 38 per cent, of ash, its constituents per cent, 

 being, 



Hygrometric water, 1 .65 



Gaseous and Bituminous matter, 14.17 



Ash ; Iron, silex and lime, 37.82 



Saline matter, principally sulphate of iron, from decomposed 



pyrites, - 4.35 



Carbon, 44.18 



102.17 



Excess as before from the peroxidation of the iron. 



This result is only so faif useful as that it shews that considerable 

 heating may go on without much, if any, apparent change in the struc- 

 ture and appearance of the coal, and that this may take place after so 

 long an interval as ninety-five days ! after being damaged by salt water, 

 and I have therefore thought it highly worthy of being placed upon 

 record. 



