96 



NODULES AND CONCRETIONS. 



Upper bands in Uppe 



Gallery. 



Hi 



Chelt 



en 



ham. 



Wall -case 44. 



(See "Memoir on Map 44 of the Geological Survey," by 

 Ed. Hull, F.G.S., p. 24.) 



49. — Septarian nodule, with iron pyrites filling cracks 

 in the interior. Found in the walls of a copper-lode, 3q 



fathoms from the surface, (see also 



Case 



I) 



50. — Sections of coprolitic nodules, polished to show 



the internal structure. 



51. 



\ of Forth, & 

 from Plastic 



•JS 



ear 



Wimbome Minster. Dorset, 



* 



52. — Concretionary nodules of iron pyrites in fel- 



Gwernyfid rocks, Wye, near Builth, Brecon- 



■ 



spathic rock. 

 shire. 



53. — Nodular concretions of iron pyrites from the 



Chalk. — Compton Bay, Isle of Wight. 



54. — Concretion of iron pyrites from the Chalk. — Comp- 

 ton Bay, Isle of Wight. 



- 55. — Cannon ball, forming a centre surrounded by 

 concreted ferruginous matter. 



56. — Portions of an iron grating left on the Bell Rock, 

 and exposed to the alternate action of the air and sea by 

 the rise and fall of the tides from 1811 to 1853. 



The two last-mentioned specimens (Nos. 55 and 56) are 

 placed here to illustrate the rapid destruction of iron by 

 the process of oxidation or rusting, and its conversion into 



a carburet of iron, No. 56. 



57. — An old horse shoe, found in the river Trent, at 

 Nottingham, exhibiting the agglutinating power of iron 

 while undergoing oxidation. 



58. 



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