146 



These springs have aslso been noticed by Frassoni, in 1660, in a 

 pamphlet entitled Thermce Montis Gibii ; by Ramazzini, in 1698 ; and 

 by Vallisneri, in 1711. 



Bituminous substances in various degrees of solidity and purity 

 are found in several parts of England ; as is indeed the case in most 

 parts, in the neighbourhood of which coals are found to exist. 



Dr. Plott, in a discourse concerning perpetual sepulchral lamps, 

 read before the Dublin Society, 1684 *, mentions that at Pitchford, 

 in Shropshire, there is a naphtha or liquid bitumen, that constantly 

 issues forth with a spring there, and floats upon the water. This, 

 the Doctor thinks, might be separated, before it joins the water, into 

 a channel of its own ; and so conveyed to a place thought most con- 

 venient for such a lamp, into which it should perpetually distil, as 

 it does now into the fountain. For, the Doctor observes, a brush 

 or wick of asbestos, or of gold wire, might be employed, and if the 

 oil be properly disposed, then, says the Doctor, we have an oil as 

 everlasting as our wick ; nor need we fear any extinction, if en- 

 closed in a tomb or vault under ground, in never so damp and 

 moist a place ; it being, he adds, the characteristic of bitumen, to 

 burn best where there is moisture, as is evident upon affusion of 

 water upon sea coal. 



Among the inflammable minerals of Derbyshire, Mr. Mawes, 

 whose opportunities of observation are as great, as his collection is 

 interesting, observes, the most remarkable is the elastic bitumen, 

 in its various states -j~. It is generally, he says, found between 

 the stratum of schistus and lime-stone ; rarely in small cavities, 

 adhering to the gangart, which sometimes contains lead ore, fluor, 

 &c. When first detached, its taste is very styptic, as if blended 

 with decomposed pyrites. It varies in colour, from" the blackish 

 or greenish brown to the light red brown, and is easily compressed ; 



* Mr. Ayscough's C3tal. 4811. Plut. vi. E. vol. i. 34, 1684. 





 t The Mineralogy of Derbyshire, by John Mawes, p. 92, 



