134 The Palceolithic Implements and Gravels of Knowle, Wilts. 



Two features noticeable on the surface of a considerable number, 

 both of worked and unworked flints, call for special remark. One 

 is the highly polished appearance of the stones. They are seldom 

 completely polished, for bands of varying hardness in the stone 

 show varying degrees of polish, and the high gloss is most frequently 

 produced upon the later fractured surfaces. It should be mentioned 

 that these polished stones come more particularly from the bottom 

 of the pit, where the gravel is rather smaller, and the flints are 

 embedded in a quantity of fine sand. 



Many suggestions have been made as to the probable cause of 

 the highly glossy surfaces. The most obvious explanation is that 

 they are due to the action of wind-blown sand, but while to us this 

 would fully account for the phenomenon, the unusual brilliancy of 

 the surface has caused other suggestions to be put forward. 



Another explanation, which has met with considerable support, 

 is that a varnish of soluble hydrate of silica has been left upon the 

 flints. To this solution of the problem there are, however, important 

 objections. This soluble hydrate, as is well known, can be dissolved 

 in heated water in the presence of an alkali. It is obvious, 

 then, that the action of a warm caustic potash solution would 

 effectively destroy a varnish of this nature. The experiment thus 

 suggested, we have carried out, and have in our possession a small, 

 extremely glossy stone, one end of which has been immersed in 

 boiling potash for some time. It is still absolutely impossible to 

 distinguish one end of the stone from the other, a fact which should 

 conclusively prove the absence of any soluble hydrate of silica. 



A further most important objection to the silica varnish theory 

 is afforded by a careful survey of many of the flints in question. 

 It seems barely conceivable that a fluid of any kind could touch 

 certain projecting ridges and points, without glazing also the de- 

 pressions which lie between them. That the hollows have usually 

 escaped, while projections have been affected, is well shown on 

 many of the specimens, and is to our minds a very telling argument 

 against the glazing by a secondary deposit. 1 



1 See specimens Nos. 21, 99, 111, 114, in North Wilts Museum. 



