FREESTONE. 21 



loam instead of mortar ; the sand of which fluxes,* 

 and runs, by the intense heat, and so cases over the 

 whole face of the kiln with a strong vitrified coat 

 like glass, that it is well preserved from injuries of 

 weather, and endures thirty or forty years. When 

 chiselled smooth, it makes elegant fronts for houses, 

 equal in colour and grain to the Bath stone ; and 

 superior in one respect, that, when seasoned, it does 

 not scale. Decent chimney-pieces are worked from 

 it, of much closer and finer grain than Portland ; 

 and rooms are floored with it ; but it proves rather 

 too soft for this purpose. It is a freestone, cutting 

 in all directions ; yet has something of a grain 

 parallel with the horizon, and therefore should not 

 be surbedded, but laid in the same position that it 

 grows in the quarry.f On the ground abroad this 

 fire-stone will not succeed for pavements, because, 

 probably, some degree of saltness prevailing within 

 it, the rain tears the slabs to pieces. J Though this 

 stone is too hard to be acted on by vinegar, yet 

 both the white part, and even the blue rag, ferment 

 strongly in mineral acids. Though the white stone 

 will not bear wet, yet in every quarry, at intervals, 

 there are thin strata of blue rag, which resist rain 

 and frost, and are excellent for pitching of stables, 

 paths, and courts, and for building of dry walls 



* There may, probably, be also in the chalk itself, that is 

 burnt for lirne, a proportion of sand ; for few chalks are so pure 

 as to have none. 



f To surbed stone is to set it edgewise, contrary to the pos- 

 ture it had in the quarry, says Dr. Plot. Oxfordsh. p. 77- But 

 surbedding does not succeed in our dry walls ; neither do we 

 use it so in ovens, though he says it is best for Teynton 

 stone. 



J " Firestone is full of salts, and has no sulphur ; must be 

 close-grained, and have no interstices. Nothing supports fire 

 like salts ; saltstone perishes exposed to wet and frost." PLOT'S 

 Staff, p. 152. 



