180 THE OLD RED SANDSTONE. 
pendently of their well-marked organisms, there is a simple 
test through which the lignites of the newer formations may 
be distinguished from the true coal of the carboniferous sys- 
tem. Coal, though ground into an impalpable powder, re- 
tains its deep black color, and may be used as a black pig- 
ment; lignite, on the contrary, when fully levigated, assumes 
a reddish, or, rather, umbry hue. 
I have said that the waters of the well of the coal-heugh 
are chalybeate —a probable consequence of their infiltration 
through the iron oxides of the superior beds of the formation, 
and their subsequent passage through the deep red strata of 
formations beneath the only one at which the object of his search 
could have been found. Mr. Murchison thugsrelates the story : — 
«‘ At Tin-y-coed I found a credulous farmer ruining himself in ex- 
cavating a horizontal gallery in search of coal, an ignorant miner 
being his engineer. The case may serve as a striking example of the 
coal-boring mania in districts which cannot by possibility contain that 
mineral; and a few words concerning it may, therefore, prove a sal- 
utary warning to those who speculate for coal in the Silurian Rocks. 
The farmhouse of Tin-y-coed is situated on the sloping sides of a hill 
of trap, which throw off, upon its north-western flank, thin beds of 
black grauwacke shale, dipping to the west-north-west at a high an- 
gle. The color of the shale, and of the water that flowed down its 
sides, the pyritous veins, and other vulgar symptoms of coal-bearing 
strata, had long convinced the farmer that he possessed a large hid- 
den mass of coal, and, unfortunately, a small fragment of real anthra- 
cite was discovered, which burnt like the best coal. Miners were 
sent for, and operations commenced. To sink a shaft was imprac- 
ticable, both from the want of means, and the large volume of water. 
A slightly inclined gallery was therefore commenced, the mouth of 
which was opened at the bottom of the hill, on the side of the little 
brook which waters the dell. I have already stated that, in many 
cases, where the intrusive trap throws off the shale, the latter pre- 
serves its natural and unaltered condition to within a certain distance 
