MINERALOGY OF ARRAN. 351 



fcutit expands to a great extent below the sea. If ever it ner in which it 

 be convenient to work it, I conceive it should not be by Wroug ht, 

 sinking pits, but by sinking in the stratum itself, and draw- 

 ing it up the inclined plane of sandstone, on which it rests, 

 by carriages running upon rollers. 



This coal, being esteemed pure carbon, and capable of With the iron- 

 producing a most intense heat, I am surprised it never has made 'profit- * 

 been applied to the smelting of iron, and other fornacicable. 

 uses. The ironstone here seems inexhaustible, and of 

 excellent quality. A harbour might be scooped out of one 

 of the ledges of limestone, which enclose the coal-field; 

 which would cost nothing, as the limestone would repay 

 the expense with profit. From this, the coal and ironstone 

 might be exported to a situation favourable for an iron- 

 work. 



Some strata of bituminated shiver, or shale, of a black Bituminous 

 colour, are visible, not only in the coalfield ; but many s ' 

 arc visible, for a great extent, on each side of it. These 

 strata sometimes throw out an efflorescence of sulphate of 

 magnesia. 



But in one of the seams of coal which Mr. Cowie had A stratum 

 wrought in the way called open stretch, for the purpose of x ^v ^r^' 

 burning limestone, I observed a highly bituminated species tumen between 

 of till, of a black colour. This appeared so extraordinary, ^"^coal ° f 

 that I requested Mr. Cowie to write down a description of 

 it, which follows. 



* The seam of coat, at the Cock of Arran, wrought by 

 James Cowie, is first about ten inches, then eight or tan 

 inches of a dauchy till, then twenty inches of coal. The 

 dauch which separates the two seams of coal, is arranged 

 in this manner //XX^^/vv* like the back-bone of a 

 fish, and rises in large pieces, but parts in the middle. The 

 till between the two seams of the coal serves to burn lime.' 



Mr. Cowie added, that the dauch- was always mixed with Mixed for 

 the blind coal in burning lime. That it seemed to kindle burninglhne * 

 more readily than the coal; and the only difference was, 

 that the dauch always left a large guest (cinder) ; whereas 

 the coal burnt into a fine white ash, of very small quantity. 



Here, then, are highly bituminated strata of clay, not 

 only connected with blind coal, but one interposed between 

 two seams of that fossil. 



5 Our 



