OLD COAL-PIT WATEB UPON IRON. 



35 



No. 6 is a most interesting specimen of a portion of cast 

 iron tubbing, of an inch in thickness. One side of it appears 

 to have been built into a wall, or somehow covered with a 

 coat of lime, for it is still coated with whitewash, except a 

 portion near the edge, which has a little yellow ochre upon it. 

 Now where the thin covering of lime remains, the iron on 

 that side shews no signs of decomposition, whilst on the other 

 side, where there is no lime, the iron in the centre of the 

 casting has been eaten away to the depth of one-fourth of 

 an inch. 



The effect produced upon the wrought irons : — 



No. 7 is a chisel of wrought iron, faced with steel, ten 

 inches in length, by three-quarters of an inch in diameter. 

 The iron is corroded and eaten into so as to shew the threads 

 of which it is composed, in some places, to the depth of two- 

 tenths of an inch. This is most marked where the iron and 

 steel join. The steel itself has scarcely been acted upon at 

 all, and the broken point exhibits a fracture just as if it had 

 only been made a few days. 



No. 8 is the outside of a Ij inch axle, which was attached 

 to one of the waggons to which the cast iron wheels previously 

 described belonged. The thickness of it is about one-third 

 of an inch, and it appears as if it had shelled off from the 

 sounder part of the axle. It has not the black plumbago 

 appearance which the cast iron before noticed exhibits, but 

 shews more of the characters of ordinary rust, produced by 

 oxidization of the metal. 



No. 9 is a wrought iron hammer, with a handle of ash fixed 

 in it. This specimen appears to have been acted upon more 

 than any of the other specimens of wrought iron, being in 

 some parts, especially the faces, corroded to the depth of 

 one-third of an inch. The threads of iron and every bend in 

 them are beautifully shewn all over the surface of it. 



There was another hammer, with steel face, found in the 

 pit. This was corroded in a similar manner to that last 



