344 Mr. Finch's Account of a Pseudo-Volcano, [May, 



2. Mineral Tar. — This occurs only in one situation, which 

 appears to be at the cropping out of a thin bed of coal. I only- 

 found a small quantity, more or less viscid, and mixed with black 

 earth. 



3. Coal. — Near the farm-house is a small hollow, caused 

 either by an old shaft, or by the sinking of the ground from the 

 fire beneath. Four feet from the surface is a bed of coal, three 

 feet in thickness. This may be seen without the trouble of 

 descending a shaft for that purpose. It shows the coal most 

 accurately between roof and floor, dipping south. Being so 

 near the surface, it appears in very small lumps, in the state 

 which the miners term rotten. Under this bed of coal is a 

 stratum of clay six inches in thickness, which contains vegetable 

 impressions in abundance. 



Saline Minerals. 



4. Sulphate of Alumina occurs as an efflorescence in strata 

 of calcined clay near the surface. It is formed from the burning 

 of the shale, which contains a large portion of alumina, and 

 which is supplied with sulphuric acid from the pyrites. 



5. Muriate of Ammonia, combined ivith a small Proportion of 

 Sulphate of Ammonia. — Produced in beautiful crystals of the 

 usual forms ; also, a crystallization, which I believe has not been 

 hitherto noticed, at least not by the authors I have consulted. 

 It is a very thin hexagonal table, having two of the opposite 

 sides broader than the others. It occurs in clusters covering the 

 other crystals, which are four-sided pyramids joined base to 

 base. 



6'. Sulphate of Zinc. — This rare substance has hitherto been 

 found only at Holywell, in North Wales. The taste is nauseous- 

 metallic, and it occurs combined with aluminous earth. I should 

 have distrusted my own opinion on this substance ; but Mr. 

 Dalton, of Manchester, being in Birmingham for a short time, 

 I submitted it to his judgment, and he allows me to make use 

 of his authority in determining its nature. 



Earthy Minerals. 



7. Sulphate of Lime. — The upper stratum of sandstone is 

 penetrated in several parts by tins substance, which has been 

 noticed as occurring in many coal-fields. It here appears 

 remarkable merely from the red base to which it is attached, 

 giving it a porphyritic appearance. It is rather abundant. 



8. Porcelain Jasper. — Formed by the calcination of almost all 

 Ihe beds of clay which lie over the burning coal, and consequently 

 very abundant. It presents almost every variety of colour, and 

 varies from five to forty feet in thickness, 



9. Newest Floetz Trap, Basalt, or Rowley Rag. — This sub- 

 stance is well known to geologists, in consequence of the 

 scientific experiments of the late Mr. Gregory Watt, and the 



