(* 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.)
(** To surbed stone is to set it edgewise, contrary to the posture 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.)
(*** '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.)
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 very hard
and heavy, and of a firm, compact texture, and composed of a
small roundish crystalline grit, cemented together by a brown,
terrene, ferruginous matter; will not cut without difficulty, nor
easily strike fire with steel. Being often found in broad flat pieces,
it makes good pavement for paths about houses, never becoming
slippery in frost or rain; is excellent for dry walls, and is sometimes
used in buildings.
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