1849.] Miscellaneous. 413 



one large layer of bright coal and a number of dull ones with minute bright folia 

 amongst them on both sides of the bright layer. 



Examination. 

 The sp. gravity of a carefully chosen piece with part of a globular con- 

 cretion attached is, , 1. 26 



It contains in 100 parts ; Hygrometric Water, . . , 3. 90 



Gaseous matter, 18. 90 



Carbon, 61. 75 



Ash, 16. 25 



100. 80. 



It will be seen that this makes it an inferior coal to the ball coal formerly 

 analysed, but this is of little consequence, since it is not the quality of the coal, 

 but its singular structure, which we are now investigating. I have been informed 

 by Captain Powell of the P. and Or. Company's service, that in a steamer in 

 which the coals were found to be on fire, but were extinguished, that the whole 

 of the heated mass (of English Coal) was more or less softened, so that they were 

 obliged rather to cut it like soft clay, so as to dig it out for throwing over- 

 board ! If this was the effect of heating under the light pressure of a steamer's 

 coal-bunker, we may readily suppose that a whole bed of coal may, when heated 

 under the pressure in the mine, so far soften as upon gradual cooling to be at 

 liberty to affect this semi-concretionary form, as so many half liquified bodies 

 do, and as we see is shewn to be in granites and traps, when they decompose, 

 their tendency also. But as we do not yet know how far this structure of the 

 coal extends, and how it passes into the common laminary form and cubical frac- 

 ture, we must suspend our judgment and our speculations as to what can have 

 really given rise to this singular variety of coal. At present the few specimens 

 we possess do not allow me to sacrifice any of the complete little shining nodules 

 which may have an homogeneous structure, for examination. 



