50 Mr. Winch on Grey Whin. [Jan. 



and the nature of its component parts, it is both heavy and 

 tough, requiring a smart blow ofthe hammer to break it. Before 

 the blowpipe, it fuses without much difficulty, into a pale-brown 

 glass ; it is not magnetic like basalt. At St. Anthon's colliery 

 (see Geological Transactions, vol. iv. p. 41), the bed lies nearly 

 104 fathoms from the surface of the earth, and is a foot in 

 thickness ; its situation is between a stratum of strong white 

 post (sandstone) seven feet thick, and a stratum of blue metal 

 (shale, slate clay) eight and a half feet thick. In Walbottle 

 Dene, five miles west of Newcastle, a similar stratum creeps out 

 by the edge of the brook ; but its thickness or relative pusition 

 cannot there be so accurately ascertained as at St. Anthony's, where 

 a shaft has been sunk through it. Whether this be a continua- 

 tion ofthe same bed, I cannot determine; but the high main coal 

 cropping out at Benwell Hills, two miles to the east of Walbottle, 

 and this bed lying '29 fathoms below that seam, I am inclined to 

 considerthem one and the same, notwithstanding the stone is finer 

 grained at the latter place ; for all our coal strata rise to the clay 

 in succession towards the west and south-west. 



It is by no means improbable that similar beds may be known 

 to exist in other districts ; but never having heard of a stratum 

 of compact felspar and mica, as a member of a coal formation, 

 you will oblige me by giving publicity to this short notice through 

 the medium of your journal. 



I have the honour to be, Sir, 



Your most obedient servant, 



N.J. Winch. 



Article VI. 



Queries on the Plumbago formed in Coal Gas Retorts. 

 By the Rev. J. J. Conybeare, MGS. 



(To the Editor of the Annals of Philosophy.) 



MY DEAR SIR, Bath Boston, Dec. 15, 1822. 



The very general use of coal gas, and the degree of scientific 

 information mostly to be found in those connected with its manu- 

 facture, render it probable that for many persons the remarks 

 which I am about to offer will possess but little of novelty. As, 

 however, I am not aware that this subject has yet been noticed 

 in any periodical or other publication, 1 venture to intrude them 

 on the notice of your readers, rather indeed in the hope of 

 obtaining further information from those who are more compe- 

 tent than myself, than of adding much to the public stock. 



