O F S E L B O Pv N E. 9 
whole face of the kiln with a ftrong vitrified coat like glafs, that 
it is well preferved from injuries of weather, and endures thirty 
or forty years. When chifeled fmooth, it makes elegant fronts 
for houfes, equal in colour and grain to the Bath ftone; and fu- 
perior in one refped, that, when feafoned, it does not fcale. De- 
cent chimney-pieces are worked from it of much clofer and finer 
grain than Portland; and rooms are floored with it; but it proves 
rather too foft for this purpofe. It is a freeftone, cutting in all 
diredions; yet has fomething of a grain parallel with the horizon, 
and therefore Ihould not be furbedded, but laid in the fame pofition 
that it grows in the quarry On the ground abroad this fire- 
ftone will not fucceed for pavements, becaufe, probably fome de- 
gree of faltnefs prevailing within it, the rain tears the flabs to 
pieces^. Though this ftone is too hard to be aded on by vinegar; 
yet both the white part, and even the blue rag, ferments ftrongly 
in mineral acids. Though the white ftone will not bear wet, yet 
in every quarry at intervals there are thin ftrata of blue rag, which 
refift rain and froft; and are excellent for pitching of ftables, paths 
and courts, and for building of dry walls againft banks ; a valuable 
fpecies of fencing, much in ufe in this village, and for mending of 
roads. This rag is rugged and ftubborn, and will not hew to a 
fmooth face ; but is very durable : yet, as thefe ftrata are fliallow 
and lie deep, large quantities cannot be procured but at confider- 
able expenfe. Among the blue rags turn up fome blocks tinged 
<= To furbed ftone is to fet it edgewlfe, contraiy to the pofture it had in the quaiT}% 
fays Dr. ?lot. Oxfordjh. p. 77. But furheddmg does not fucceed in our dry wallsj 
neither do we ufe it fo in ovens, though he fays it is beft for Teynton ftone. 
f " Fireftone is full of falts, and has no fulphur : muft be clofe grained, and have no 
*' interftices. Nothing fupports fire like falts; faltftone perilhes expofed to wet and 
♦< froft." Plot's Staff, p. 152. 
C with 
