the Granites of the South-east of Ireland. 



27 



grained granite from Kiltealy^ on the Wexford slope of 

 Blackstairs. 



No. 8. BalbjleUjh. — Specific gravity^ 2'627. A fine-grained 

 granite taken fi'om near Poubnounty Bridge, at the south- 

 west extremity of the granite chain. 



Calculating the atomic quotients from Table I., we construct 

 the following Table, containing the values of a, h, c, and of Q, 

 F, M, calculated from equations (1). 



Table II. — Atoms of Granitic ]\Iinerals. 



Calculating, by the method already described, the per-centages 

 of quartz, felspar and mica, contained in the different granites, 

 Ave find the following : — 



Table III. — Per-centages. 



From the foregoing calculations, it follows, that, with the ex- 

 ception of the Ualkey granite, the granites of the main chain 

 examined might be represented by combinations of quartz, fel- 

 spar and mica, in which the quartz is the most regular mineral, 

 considered with reference to its pcr-centage. 



The following Table contains analyses of granites belonging to 

 the second group, and supposed to be newer than the others, 



