310 A brief Account of the 



bed forms a black glass. Mr. Aikin, in his Tour, p. 201, 

 mentions the Longmount to be composed, so far as his 

 observations extended, of a very shivery kind of schistus. 

 It certainly presents that appearance on its east side, near 

 the Strettons. But Dr. Townson says, the nature of the 

 rock, in general, is " compound sandstone, i. e. a stone 

 which, instead of being formed of grains of quartz, is 

 formed of grains, or very minute fragments, of other kinds- 

 of stone. These, here, seem to be of an argillaceous and 

 jaspidcous nature, mixed with a few grains of feldspar*." 



The Wrekin is chiefly composed, I believe, of a reddish 

 chert. Mr. William Reynolds informs me, that prodigious 

 masses of granulated quartz are imbedded in it, and much 

 feldspar, and that a quantity of red mica is also found at 

 the south-west end of the hill. The Stipcr stones are a 

 granulated quartz ; and they are perhaps the highest ground 

 in Shropshire, except the hills near Oswestry, and those 

 are a coarse grained sandstone. Near the Cardington hills 

 Mr. William Reynolds found a quartz f that he thought as 

 good, or better, than the Carreg china of Caernarvonshire, 

 which is exported for the use of the English potteries. He 

 has since found a granulated quartz, in the Wrekin and 

 Arcall hills, which seems likely to answer the same purpose 

 for the pottery, and which has the convenience of being 

 near established potteries, and a navigable river. With the 

 same advantages, that near Cardington would be very valua- 

 ble, as there is a steatitic clay there, which was long used 

 in the Caughley china-works, at a considerable expense of 

 land carriage. Pitchford, about seven miles south-east of 

 Shrewsbury, is a red sandstone, approaching the surface in 

 many places, and from which exudes a mineral pitch. The 

 same substance is gathered from a well in the neighbour- 

 hood, and in some quantity in warm weather; but in winter 

 very little is seen floating on the water. From the rock is 

 extracted an oil called Betton's British oil. The experiment 

 was first tried at Brosely (at a place still called the Pitch- 

 yard), about fourscore years ago, or more, and an account 

 of which was published in No. 228 of the Philosophical 

 Transactions : from near that period the Pitchford rock has 

 been gotten for that purpose, and sometimes 20 ton, or 

 more, used in a year, for which the manufacturer paid 5s. 

 per ton. It was carried from thence to Shrewsbury, where 

 the oil was procured by distillation ^ but the process is kept 



* Tracts, &:c. p. i86. 



+ The first species, second family of the siliceous genus of Kirwaij. 



secret : 



