538 rHILOSOPHICAL TRANSACTIONS. [aNNO I762. 



cliffs, and beati^ off large pieces of them) the cliffs continue to smoke, and 

 sometimes to burn with a visible flame; which during the summer-months is 

 frequently observed in the night-time. On examining these cliffs, in the year 

 1759, Mr. S. discovered a great quantity of pyrites, not in any regular strata, 

 but interspersed in large masses through the earth, and which proved to be 

 martial; of marcasites, which yielded near one tenth part of common sulphur; 

 of cornua ammonis of different sizes, and other shells, but of the bivalve class, 

 which were crusted over, and as it were mineralized with the pyritical matter ; of 

 belemnites, also crusted over with the like substance: and the cliffs, for near 2 

 miles long, and from the surface, to 35 or 40 feet deep, even to the rocks at 

 high water mark, were one bed of a dark coloured loam, strongly charged with 

 bitumen. He found also a dark coloured substance, resembling coal-cinder; 

 some of which being powdered, and washed in distilled rain water, on filtrating 

 the water, and evaporating it slowly to a pellicule, its salts shoot into fine crys- 

 tals, and appear to be no more than a martial vitriol: one ounce of this cinder- 

 like substance yields one drachm of salt. He gathered up about 100 lb. weight 

 of the different kinds of those pyritae, marcasites, &c. which were laid in a heap, 

 exposed to the air, and every day sprinkled with water: the consequence was, 

 that in about 10 days time they grew hot, soon after caught fire, burned for se- 

 veral hours, and fell into dust. Hence therefore it is imagined that these martial 

 and sulphureous fossils, by being exposed to the air and wet, by being agitated 

 by the beating of the sea, and by being electrified as it were by the subtle flame 

 of the lightning, take fire, which is favoured by the bituminous particles con- 

 tained in the loam, and burn till all their phlogiston is consumed, and their iron 

 or martial earth is dissolved in the acid of sulphur ; which constitutes the martial 

 vitriol, found to be near the one-eighth part of this cinder-like matter. 



When the cliffs were observed to burn in the night-time, the flame was 

 plainly perceived by a spectator at a distance ; but when he drew near to the 

 place seemingly on fire, he could perceive a smoke, but no flame. • In the day- 

 time nothing but a smoke was perceived, except the sun shined, when the cliffs 

 appeared at a distance as if they were covered with pieces of glass, which reflected 

 the sun's meridional rays ; but on drawing near to the places where these lumi- 

 nous appearances were perceived, they disappeared, and the cliffs seemed to be 

 covered with smoke, which stunk of a bituminous and sulphureous matter. 



Mr. S. had also been an eye witness of the same kind of flame arising from 

 the Lodes in Cornwall, especially such as contained a greiit quantity of mundic 

 and martial pyrites. Three times he had seen this flame arise from the earth in 

 the night, and once in the middle of the day. In the night a person standing 

 at a Iktle distance, would imagine that the place was all on fire, and even on 

 drawing near the same he perceives himself surrounded with flame, but is not 



