HISTORY OF STAFFORDSHIRE. [137 



Feet In. 



1 . Dark chinch, generally about 1 6 



2. Light-coloured clay, with small round iron-stone, called white 



grains, 2 6 



3. Main iron-stone, in balls or nodules, involved in clunch : of 



this mine there are three distinct measures, 3 



4. Table batt, a smooth level-faced schistus, sometimes thicker, 3 



5. White clay, containing white iron-stone, 1 6 



6. Heathing coal, in three distinct layers : good coal, 6 



7 Measures of clunch and white-rock to the pot-clay, which is 



about 16 or 20 yards below the main coal at the lye, where 

 it is principally got, the clay being there nearer the surface 

 of the ground, and of a better quality than in most other 

 places which have been tried. This is what is called Stour- 

 bridge clay, and, from its quality of resisting the most vio- 

 lent heat, has caused the establishment of the glass-manu- 

 factories in this neighbourhood. 



Iron-stone is found in several of the measures or strata, as be- 

 fore-named. Of these two only are worked for the ore, namely, 

 that which lies immediately under the broach coal, and that which 

 lies under the main coal. In the neighbourhood of Wednesbury, 

 the former bed is worked ; and in the other parts of the country, 

 the latter is most considerable. The iron-stone is generally got 

 in coal-works after the coal has been extracted, particularly where 

 it lies at a moderate depth from the surface of the ground, that the 

 expence of sinking pits, and raising it, may be less. 



Iron-stone, when dug, is put up in masses called blooms, the 

 dimensions of which are three feet by four feet, with a height of 22 

 inches, and the weight is estimated at 35 hundred, each hundred 

 being 120 pounds. Sometimes 1000 or 1200 such blooms are good 

 from one acre of good mine. The quantity of iron-stone now 

 (1800) got, is sufficient to keep at work about 14 smelting furnaces 

 in the coal country, which produce annually about 18,000 tons of 

 pig-iron ; all of which, and more, from other countries, is worked 

 up in the founderies and forges of this neighbourhood. 



Spars, calcareous and gypseous, chiefly the latter, in very thin 

 plates, are sometimes found on the coal : when this abounds, its 

 vitriolic acid forms with the coal in the tire a sulphur which 

 smiths observe to be injurious to their iron, they therefore avoid 

 using such coal. 



The coal of this country in small pieces, does not cake or con- 

 glutinate in the tire, as that of Newcastle-upon-Tyne, and some 







