FREESTONE. 9 



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 sea- 

 soned, it does not scale. Decent chimneypieces 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 firestone will not 

 succeed for pavements, because, probably some degree of salt- 

 ness 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 

 against banks, a valuable species of fencing, much in use in 

 this village, and for mending of roads. This rag is rugged 

 and stubborn, and will not hew to a smooth face, but is very 

 durable ; yet, as these strata are shallow, and lie deep, large 

 quantities cannot be procured but at considerable expense. 

 Among the blue rags turn up some blocks, tinged with a stain 

 of yellow, or rust colour, which seem to be nearly as lasting as 

 the blue ; and every now and then balls of a friable substance, 

 like rust of iron, called rust balls. 



In Wolmer Forest I see but one sort of stone, called by the 

 workmen sand, or forest stone. This is generally of the colour 

 of rusty iron, and might probably be worked as iron ore ; is 



* May not the fact here noticed shew the possibility of what are called 

 vitrified forts being produced by fires lighted for signals, or some other 



purpose, as an instance is here given of heat causing sand to flux ED. 



There may probably be also in the chalk itself that is burnt for lime a 

 proportion of sand ; for few chalks are so pure as to have none. 



f To surled stone is to set it edgewise, contrary to the posture it had 

 , in the quarry, says Dr Plot, Oxfordshire, 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. 



1 " 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. 



