550 
I 
Mr. Winch on the Eastern Part of Yorkshire. 
once ignited by a small quantity of brushwood, I suspect some 
portion of bitumen must be blended with it. 
For the process of manufacturing alum, as practised at present, 
I beg leave to refer to the Appendix to Aikin’s Chemical and Mine- 
ralogical Dictionary. 
At the time when the history of Whitby was published, alum 
works were carried on at Loftus, Boalby, Kettleness, Sandsend, 
Eskdaleside, Littlebeck, Stoupbrow, and Peak, but had previously 
been discontinued at Gisbro’, Ayton, Carlton, Osmotherly, and 
other inland places. 
At the depth of 200 to 250 feet from the top of the bed of alum 
shale, it is intersected and mixed with layers of sand for the space 
of 50 to 70 feet in thickness. These bands of sand are blended with 
day, and contain nodules of thin bands of ironstone, in one of 
which large pectenites are found ; in another a species of oyster ; 
and in a third a shell resembling a cockle. This admixture of sand 
and clay is observable in the cliffs wherever the alum rock is 
exposed to view. Besides the fossils enumerated, madreporite, 
(See Jameson, edit. 2d, and Aikin’s Min.) with liquid bitumen, 
occurs in this rock ; and the tusks of sharks are occasionally scattered 
through it. 
