ae. oe ees 
aerial ace: 
419 
communicating to the Academy a brief notice of some re- 
searches which I had made in relation to ‘ the nature and re- 
lative proportion of the alkalies of the felspars occurring in the 
vicinity of Dublin.’ In this notice I gave the results of my 
examination of four different specimens of felspar from diffe- 
rent localities near this city, and stated that my experiments 
rendered it impossible for me to adopt the views submitted to 
the Academy at its previous meeting by Sir Robert Kane, viz., 
that the potash found by him in numerous analyses of speci- 
mens of granites from various parts of ‘ the great mass which 
extends from Dublin into the county of Wicklow, should in 
most cases be considered 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.’ 
‘* Upon this paper Sir Robert Kane made some remarks, 
which are, no doubt, in the recollection of several members of 
the Academy; and to these, particularly such of them as I 
considered to have a relation to the subject under discussion, I 
took an opportunity of replying to the best of my ability. 
These matters I recapitulate here, not for the purpose of re- 
viving the discussion which took place,—though I, of course, 
feel no indisposition to discuss in a suitable spirit any scientific 
question to which I have paid attention,—but with the view 
of enabling the Academy to understand why I am now tres- 
passing on its indulgence. 
*< An abstract of my notice first referred to appeared shortly 
after in the Proceedings (see pages 379-82), and in turning to 
it, and throwing my eye over the observations attributed to 
Sir Robert Kane (see page 382), I was, I confess, not a little 
surprised to find the following passage : 
‘<< Sir Robert Kane explained, in reference to Dr. Apjohn’s 
observations, that he had never denied that orthose or potash 
felspars were found in certain localities of the Dublin and 
Wicklow range, and that Killiney was certainly one of those, 
