NATURAL HISTORY OF SELBORNE. 11 



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.* On the ground abroad this firestone will not 

 succeed for pavements, because, probably some degree of 

 saltness prevailing within it, the rain tears the slabs to 

 pieces.! Though this stone is too hard to be acted on by 

 vinegar, yet both the white part, and even the blue rag, 

 ferments 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 



* To surbed stone is to set it edgewise, contrary to the posture 

 it had in the quarry, says Dr. Plot, Oxfordshire, p. 77. But 

 surhedding does not succeed in our dry walls ; neither do we use it so 

 in ovens, though he says it is best for Teynton stone. 



t "Firestone is full of salts, and has no sulphur: must be close- 

 grained, and have no interstices. Nothing supports fire like salts j 

 saltstone perishes exposed to wet and frost." — Plot's iStaf., p. 152. 



