538 Proceedings of the Royal Irish Academy. 



from 1 to 2 feet thick, the latter abundant. None of them have been 

 ever worked to any extent so far as is known. '^•' They have the usual 

 composition of clay-ironstone, and contain about the average per cent- 

 age of iron. I have examined some of them, but only for the amount 

 of iron, and the presence or absence of sulphur and phosphorus, as a 

 more complete analysis would add nothing interesting to our know- 

 ledge of such minerals. The specimens were all obtained from the 

 neighbourhood of Coal-Island. 



Analyses of Ieok-stones, Dtjxgannox Coax-Pield. 



'B.o. 1 . — Thin seam of ironstone from above the shiniitg seam. 



Metallic iron, . . 35 "50 per cent. 

 JS'either sulphur nor phosphorus present. 



]S"o. 2. — Iron-stone nodules above G-oetxaskea coal. 



Metallic iron, . . 34-40 per cent. 

 Ifeither sulphur nor phosphorus present. 



'Eo. 3. — Iron-stone nodules above Beltibot coai. 



(«.) Metallic iron, . . 32'50 per cent. 

 Ifeither sulphur nor phosphorus. 



(5.) Metallic iron, . . 21-70 per cent. 



jN^o sulphur : a trace of phosphorus. 



{c.) ? Black band ironstones. 



Metallic iron, . . 23-50 per cent. 



~^o sulphur : a trace of phosphorus. 



!No. 4. — Iron nodules above Deeet coax. 



Metallic iron, . . 28-80 per cent. 

 . J^o sulphur : no phosphorus. 



* Traces of an old iron furnace are fonnd in the towaland of Deny, near tlie 

 road leading from Derryvale to StewartstoAvn, and a quantitj^ of slag lies about. 

 It is possible, therefore, that some of the ii'on-stones above the Derry coal wero 

 formerly smelted. 



