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«¢ A statement of this nature, made by a Member of this 
Academy about two years ago, first drew my attention to the 
subject. Many circumstances have contributed to prevent 
me from carrying on the investigation as rapidly as I could 
have wished. Nor have I even yet completed the series which 
I originally projected, as I had determined not to rest satis- 
fied until I had fairly examined the whole range of the Dublin 
and Wicklow mountains from Killiney to New Ross. Al- 
though I have not completed my series, I have, notwithstand- 
ing, examined that portion of the district which extends from 
the quarries of Dalkey to the mountain of Lug-na-quilla, and 
which, so far as Sir Robert Kane’s statement is concerned, is 
the most important; and accordingly, I do not hesitate to lay 
before the Academy, as a first contribution towards a com- 
plete chemical investigation of this subject, the results of seven 
analyses of felspars taken from different localities in these 
mountains, and of founding upon them my dissent from the 
statement made by Sir Robert Kane, viz., ‘that the felspar of 
our Dublin granites is upon the whole a soda or albitie felspar. 
«¢ These words occur in the concluding statement of a com- 
munication made to the Academy in the month of January, 
1853, in which he ‘ brought under the notice of the Academy 
the results of the analysis of the waters of the streams which 
descend from the side of the Dublin mountains, such as the 
Three Rock Mountain, with a view to illustrate the process 
of decomposition of the granite masses of these rocks, and the 
conversion of the felspathic elements into clays adapted to 
ceramic manufactures.’ 
‘In this paper we find two analyses, one that of a water 
taken from a stream running down the side of the Three Rock 
Mountain at a place called Ticknock; the other of a water 
collected from a hole in a quarry, excavated for the purpose 
of cutting out the substance so well known in this city as free- 
stone. From the residues of both these waters after evapo- 
ration, the soda greatly preponderates over the potash, in the 
