Hardman — On the Carboniferous Dolomites of Ireland. 719 



Analysis. 



Carbonate of lime, . . ■ 99-25 



,, magnesia, 0*70 



,, iron, trace 



99-95 



The iron present was hardly sufficient to give the pale yelloTv 

 colour to the mass. The parent rock of these stalagmites being so 

 very magnesian, we should expect to find a very appreciable amount 

 of magnesia in them if, as is thought by so many, the carbonate of 

 magnesia in limestone rocks is so very soluble. But what can have 

 become of it ? for I shall show presently that the waters of limestone 

 districts contain a very trifling amount of magnesia. 



It is hardly conceivable that, were the carbonate of magnesia in 

 such rocks the most soluble in weak carbonic acid, there should be 

 barely traces of it in these deposits ; and from this circumstance, as well 

 as from its scarcity in spring waters, we should rather be led to infer 

 its greater insolubility, even without the experiments I have brought 

 forward. 



No. III. — Stalactites from a highly magnesian limestone, Eailway 

 bridge, Thomastown, Co. Kilkenny. 



Analysis. 



Carbonate of lime, 99-25 



,, magnesia, 0*50 



99.75 



One link in the chain is still wanting, viz., the analysis of waters 

 which have undoubtedly passed through such limestones as the above- 

 mentioned, and which have deposited stalactitic matter. Some infor- 

 mation on this point I hope to have a future opportunity of conveying 

 to the Academy, as I have commenced some analyses of the waters 

 which have dripped from the roof of the Cave of Dunmore. But I 

 am compelled for the present to fall back on the accounts of various 

 waters already published by different authors. 



In Dr. Sterry Hunt's paper on the Chemistry of IS'atural "Waters,*-' 

 a series of nineteen analyses of various American waters is given, in five 

 of which carbonate of lime is much in excess of carbonate of magnesia, 

 and in some others chloride of calcium is in very large proportion to 

 that of magnesia. In the remainder, however, the amount of carbon- 



* Op. cif., p. 92, et seq. 



B.. I. A. mOC, SER. II., VOL. II., SCIENCE. 3 JJ 



