536 Scientific Proceedings, Royal Dublin Society. 



there are valuable sands, due to the weathering of the sandstones of 

 the " Ballycastle Coal-field" (Caty), mentioned under Glass here- 

 after. Red sand suitable for foundry purposes is procured in the- 

 valley of the Lagan, and exported from Belfast. 



In the valley of the Bann is a deposit of Diatomyte, or 

 " Diatomaceous clay." This, although properly a sand, is so fine 

 that it has come to be regarded as a " clay/' and the notice of it 

 in this and other counties will hereafter be given in a subsequent 

 paper on " Slates and Clays." 



For mortar, excellent river-sand is procured from Lough Neagh,. 

 near Antrim. Near Lisburn and Ballymoney there is pit-sand ; 

 but as the latter is mixed with clay bands, it has to be carefully 

 raised. At Hollywood there is good sand ; at Ballycastle, as 

 already mentioned, there is also good sand ; and at Larne there is 

 sea-sand on the beach. 



In some places on the coast-line there are JEoHan sands, that are 

 carted inland, to be used as manure, especially on peaty soil. At 

 Red Bay the .ZEolian sands bring large rents, they being rented 

 and cultivated by the inland farmers for potatoes, to change the 

 character of the seed, a worn-out stock being renovated after it has- 

 been grown in these sands. 



Glass. — In the neighbourhood of Ballycastle there is an excel- 

 lent sand, due to the weathering and washing of the Carboniferous, 

 sandstone. This seems to have induced the manufacture of glass 

 at a very early period, possibly in prehistoric times (see ante? 

 page 265). Of late the glass trade was for the most part an export 

 of bottles to Scotland. It declined as the native coal increased in 

 price, and finally died out when the glass-house was destroyed by 

 lightning in 1850, or thereabouts. 



ARMAGH. 



A considerable portion of the county is occupied by Ordovi- 

 cians ; but none of these sandstones, or grits, seem to be favourably 

 received as a building stone. 



To the north of the county, in the Blackwater Yalley, are- 

 Carboniferous sandstones. Some of these, of reddish colours, 

 were said to be of Permian age ; but the fossils in them suggest 



