16 



NATURAL HISTORY 



sandy 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 in- 

 juries 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 Port- 

 land ; and rooms are floored with it ; but 

 it proves rather too soft for this pur- 

 pose. It is a freestone, cutting in all di- 

 rections ; yet has something of a grain 

 parallel with the horizon, and therefore 

 should not be surhedded, but laid in 

 the same position that it grows in the 



* 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» 



