Ill 
'ive 
OF CORN W A LL. 
kind. The Jlrata .of this mcruftation are as many as the fucceffive 
indurations, eafily diftinguilhed, the under-part of each Jiratumbano 
browner and more earthy, the upper-part more white and pure the 
more impure parts or the liquid fettling neared: the bottom The 
iampies I have from thefe caves, are from half inch to fix inches 
tmck, coating the protuberances, as well as the depreftions of the 
rocks they ran upon, ufually at one thicknefs ; but where the rock 
upon whicn tms fluor iixes is concave, and the edges of that con- 
cavity upon a level, the alabafter is thicker, better clouded! and of 
a cloier gram, and confequently fitter for polilhing, and making 
-arger va.es. The upper-parts of the incrustation is covered over 
With a kind of purple powder, a fort of mineral efflorefcence 1 , 
calcaneus fermenting ftrongly with acids'; in the microfcope it ap- 
pears woohy, and], kc the (hoots of damp vitriolic fubftances ; but that 
t e r aments which lhoot from vitriol are white, and the threads of 
this ialt are tranfparent purple crofting each other in all direflions. 
The learned Mr. Ray mentions the warming-ftone digged in sect vi 
Cornwall, which being once well heated at the fire, reins itsw .,,4 
warmth a great while. Dr. Riot (Oxfordihire, page 258) f ays this ' lo “- 
ftone w.ll continue warm eight or ten hours', and gives relief in 
feveral pains, particularly in thofe of the internal hemorrhoids; and 
5 rZrfr° n0m3Si ; Z °‘ COn - P a S e 2 43 . calls it, Lapis Schifios 
dufiJJ. «jr foiidijfimus apud Cornubienfes Warming-ftone. In York- 
t ' , 7 h ?T e a ftone of this property, confifting of dark-grey 
g offy tak with fo me white fpar interpofed betwixt the flakes of it, 
which Dr. Woodward (Cat vol. I. page 6 a, 0d. 7 f.) fays, the 
people lay in their beds m cold weather at their feet, becaufe, when 
once heated, it retains the heat a great while s . 
- J" a copper-mine, called Nancothan, near Redruth, they have Swi™™,. 
a ftone which they call the Swimming-ftone. It confifts of redili- ftotie ' 
near lammce as thin as paper, intending each other in all diredions, 
and leaving unequa cavities of various angles between the fepta. 
The ftmihire is therefore very cellular, and makes the ftone fo 
ight, that it fvvims on water. It is of a yellow goflan colour, and 
as to its extenour, has fome refemblance to a light kind of cavem- 
OUS calammaris which I have had from Wirkfworth, near 
or y. I have not heard of this ftone s being found any where in 
Cornwall but in this work. 
^ Suppofed to be the flowers of cobalt. 
have obferved the fame purple elHorefcen- 
cils on a damp ftuckoed wall in the chapel at 
ot. Michael’s Mount. 
c which quality however it is inferiour to the 
^pamlh Ruggiola (mentioned in Willughby’s 
travels through Spain, page 471), which are 
broad plates, like tiles, cut out of a mountain of 
red fait near Cardona, which, being well heated 
on both fides, will keep warm twenty-four hours. 
y Hill, page 553, calls this ftone the blueifti 
white brittle Telaugium. 
Of 
