BOGHEAD COAL 



409 



The Boghead coal occurs in the higher part of the Scotch coal-field, in about the 

 position of the ' slaty band ' of ironstone ; its range is not more than 3 or 4 miles in the 

 lands of Torbane, Inchcross, Boghead, Capper's, and Bathvale, near Bathgate, in the 

 county of Linlithgow. In thickness it varies from 1 to 30 inches, and at the present 

 rapid rate of consumption, it is feared it cannot last many years. 



The following section of a pit at Torbane shows that the cannel occurs in ordinary 

 coal-measures, and under circumstances common to beds of coal : 



of plants 



Boghead house-coal . 

 Arenaceous shale 

 Slaty sandstone 



Shale and ironstone, containing 

 and shells .... 

 Cement stone (impure ironstone) 

 Boghead cannel 

 Eire-clay, full of Stigmarice 

 Coal (common) 

 Black shale 

 Coal . 

 Shale 

 Coal . 

 Fire-clay . 

 Hard shale 



Thin laminae of coal and shale 

 Common coal . " . . 

 Fire-clay .... 



One of the chief characters of this cannel is its indestructibility under atmospheric 

 agencies ; for -whether it is taken from the mine at a depth of fifty fathoms, or at the 

 outcrop, its gas- and oil-yielding properties are the same. Even a piece of the 

 mineral taken out of the drift-deposits, where it had most probably lain for thousands 

 of years, appears to be just the same in quality as if it had been but lately raised from 

 the mine. 



In the earth the seam lies parallel to its roof and floor, like other beds of coal ; and 

 it is traversed by the usual vertical joints, dividing it into the irregular cubes which 

 so generally characterize beds of cannel. The roof lying above the cement-stone 

 contains remains of Calamites ; and the ironstone nodules, fossil shells of the genus 

 Unto. The floor of the mine contains Stigmaria ; and the coal itself affords more 

 upright stems of Sigillarice, and its roots (Stigmari<e) and their radicles, running 

 through the seam to a considerable distance, than the majority of coals show. In these 

 respects it entirely resembles the Pirnie or Methill seam. Most cannels afford 

 remains of fish ; but in Boghead no traces of these fossils have yet been met with, 

 although they have been diligently sought after. 



The roots in the floors, and the upright stems of trees in the seam itself, appear to 

 show that the vegetable matter now forming the coal grew on the spot where it is 

 found. If the mangroves and other aquatic plants, at the present day found growing in 

 the black vegetable mud of the marine swamps of Brasstown, on the west coast of Africa, 

 were quietly submerged and covered up with clay and silt, we should have a good 

 illustration of the formation of a bed of carbonaceous matter showing no structure, 

 mingled with stems and roots of trees showing structure, which is the case with Bog- 

 head coal, the structure being only detected in those parts showing evidence of stems 

 and roots, and not in the matrix in which those fossils are contained. 



The chemical changes by which vegetable matter has been converted into Boghead 

 cannel will not be here dwelt on ; but the chief peculiarity about the seam is its close 

 and compact roof, composed of cement-stone, and shale. This is perfectly water- and 

 air-tight, so much so that, although the mine is troubled with a great quantity of water, 

 it all comes through the floor, and not the roof. This tight covering of the coal has 

 doubtless exercised considerable influence on the decomposing vegetable matter after 

 the latter had been submerged. It is worthy of remark that, above the Pirnie or 

 Methill seam, the coal nearest approaching Boghead, a similar bed of impure iron- 

 stone occurs. 



Away from whin dykes which traverse the coal-field, there are no appearances of 

 the action of an elevated temperature, either upon the coal or its adjoining strata, to 

 give any sanction to the hypothesis, that the cannel has resulted from the partial 

 decomposition of a substratum of coal by the heat of underlying trap, the volatile 

 matters having been retained in what has probably been a bed of shale. First, it must 

 be understood that Boghead cannel, even when treated with boiling naphtha, affords 



