Lower Palmzoic Rocks of the South-East of Ireland. 



617 



Table XVI. 



Atomic Proportions of Fdstones. 



From the preceding Table we may deduce the following:— 



Table XVII. 

 Atomic Proportions of Silica, Peroxides, and Protoxides of Fdstones. 



From the sensible equality of the atomic proportions of peroxides and pro- 

 toxides in the preceding Table, it follows that the felstones may be considered 

 as Binary granites, composed of quartz and orthoclase that have cooled 

 rapidly. 



The following Table contains their mineralogical composition, calculated on 

 this supposition. 



Table XVIII. 

 Mineralogical Composition of Felstones. 



