220 Peculiar Flints in the Neighbourhood of London. 



the presence of iron. The adhesion of the flint after being 

 burnt is much less than is the case in chalk flints. 



Blackheath flints have never been used by the gun-flint 

 makers. No doubt it is possible to make gun-flints from 

 the larger specimens, but it would be with greater labour 

 than from the finer sorts of chalk flints, and the gun-flints so 

 obtained would be more brittle and less durable. 



The Blackheath flints are totally unfit for the porcelain 

 manufacture. If there were no other objection, there is fre- 

 quently, indeed generally, a portion of oxide of iron on the 

 exterior, which would spoil the colour, and generally oxide 

 of iron is present in the interior also. 



The powder also obtained by burning and grinding Black- 

 heath flints, would not be so fine. By burning a few speci- 

 mens in a common fire, and pounding them in a mortar, and 

 then comparing them with chalk flints, treated in a similar 

 way, the difference will appear most obvious. 



The Blackheath flints are admirably adapted from their size, 

 for the purpose of the patent building, after being washed and 

 put in moulds, with lime freshed slacked with hot water, then 

 a solid body is produced of appearance like Portland stone in 

 front, and said to answer exceedingly well. 



The small flints called pease and beans are used by plas- 

 terers as an ornament to their work. The only other use to 

 which they are applied is that of materials for the roads. 



Fossil remains are seldom discovered in the Blackheath 

 flints, if we except certain snail-shaped or leech- shaped 

 bodies, found also in the chalk flints of some districts, sup- 

 posed to be Alcyonites. I have broken thousands upon thou- 

 sands in search of other fossils, and until this year without 

 success. On Plumstead common I broke open a flint in which 

 was an impression of a spine ; and I broke open another with a 

 very fine impression of a spine at Chiselhurst. Mr. John 

 Alfred Burgon, F.G.S.has found two Echini and a Pecten in 

 flint on Blackheath. Still as compared with the flints of 

 other districts, fossil remains are very rare. 



The cause of this very great rarity of fossils in these flints 

 is not very obvious. Most of them are indeed too small to 

 envelope shells or even fragments of shells, but it is far from 

 being the case with them all. It is also obvious that although 

 a large number of small flints, agitated by the waters, would 

 destroy and reduce to powder any shells which might be near 

 them, yet some might notwithstanding escape, and be enve- 

 loped in the larger flints, as in the districts in which clay 

 flints abound, asWarley and St. Ann's hill; and it is not un- 

 likely that there was diffused through the water something 



