380 Scientific Proceedings, Royal Dublin Society. 



(Proc. List. Irish C. E., May, 1880), have pointed out, they give 

 uncertain results, one portion of a bed, or accumulation, being so 

 different from those adjoining. This has in a great measure led 

 to the general use of artificial cements, which can be made of a 

 uniform quality and strength. Consequently, the Irish hydraulic 

 limestones have been for years almost entirely ignored. 



Scott and others have shown that cement can be manufactured 

 from any limestone if the proper constituents be added. This, 

 however, requires considerable skill in manipulation, which is only 

 to be acquired in time by careful observation on the part of the 

 workers while making the cement. The great art in making 

 cement consists in getting materials that can be easily and cheaply 

 associated, so as at the same time to produce a good article. 

 Yarious attempts have been made in Ireland, and although as 

 good as that imported, if not better, has been made, yet the results 

 pecuniarily have not been very satisfactory. 



There are, however, some clays in Ireland that might possibly 

 give good results. Near Ballynamona, west of Cong, Co. Gralway, 

 there is a clay that was successfully used in the manufacture of 

 cement for the waterworks at Ashford, Cong (Geol. Surv. Mem.). 

 Again, the violet-coloured lithomarge found in the " Iron Mea- 

 sures," Co. Antrim, seems to have qualities identical with those 

 of the Pozzuolana of the Bay of Naples. It has not, however, 

 yet been experimented on. There are the muds of some of the 

 estuaries which ought to contain the ingredients necessary for 

 cement, if lime were added to them, or, perhaps, in some cases 

 -even without the latter. These also, however, have not as yet 

 been tried, except some in the estuary of the Slaney, Co. Wexford, 

 which are now being employed in the manufacture of a first-class 

 cement at Drinagh, south of Wexford. 



Plaster of Paris. — In connexion with the rocks of Triassic age, 

 no limestones, except the supposed Permian dolomytes, 1 have been 

 found, but in some places there are accumulations and beds of 

 gypsum. At Derrynasrobe and Knocknacran, near Carrickmacross, 

 Co. Monaghan, there is a thick accumulation, which has been proved 

 for a depth of 60 feet. Plaster of Paris was manufactured in this 



1 The dolomyte, with Permian fossils, at the Annaghone Colliery, Co. Tyrone, 

 •occurs in intimate connexion with the Trias. 



