351 



thic materials of the granite, verified by analysis, have been 

 so few, that I considered the Academy might not consider the 

 present cases as unworthy of being placed on record in its Pro- 

 ceedings. 



The analysis of these waters have placed in view another 

 fact of much interest, in regard to the geognostic character of 

 the granite of the Dublin mountains. In the waters there 

 were found both potash and soda, but the latter in very great 

 excess. This indicates that the felspar of our Dublin granites 

 is upon the whole a soda or albitic felspar granite, although 

 in particular spots orthose or potash felspar may be found. 

 This fact has been also verified by a great number of analyses 

 of specimens of granites from various parts of the great mass 

 which extends from Dublin into the County Wicklow. In all 

 the analyses made, which included both ordinary granites and 

 elvan or granite porphyries, both potash and soda were found 

 present, and the latter almost always so preponderant as to lead 

 to the conclusion that the potash should in most cases be con- 

 sidered to belong to the mica which the granite contained, and 

 that the felspar was almost exclusively an albitic or soda 

 felspar, containing only in some cases a small quantity of 

 replacing potash. 



Dr. Apjohn made some remarks on the subject of Sir R. 

 Kane's paper, eliciting some further explanations from the 

 author. 



Read, a letter from Mr. James S. Knowles, accompanying 

 a donation of a cast of an inscribed monumental stone found 

 lately in an excavation in St. Paul's Churchyard, London. 



The stone, of the monumental portion of which the accom- 

 panying cast is a fac-simile, was discovered in the process of 

 excavating for the foundations of a new warehouse for Messrs. 

 Cook, Sons, and Co., on the south side of St. Paul's Church- 

 yaixl, in the month of August, 1852. 



