﻿288 



Mr. A. L. Fletcher 



on the 



sample of coal examined, the very finely divided nature of 

 the ash might introduce a possible source of error in the 

 imperfect retention of the accumulating emanation. The ash 

 was in this case therefore mixed with the normal quantity 

 (10 grams) of borax-glass used in each separate examination, 

 and the whole fused until the ash was completely embedded 

 in the borax. This was then coarsely broken, and stored for 

 the full period of time to avoid any error in a time calcul- 

 ation of the emanation percentage present, which might arise 

 consequent upon a partial demanation only having occurred 

 in the process-. 



The borax containing the embedded ash would effervesce 

 on fusion with the carbonate fluxes^ and fairly represent in 

 this respect a rock under the same conditions. 



With regard to the altered sediments, there is no reason 

 to suppose that those which have suffered from extensive 

 regional or contact metamorphism should on that account 

 show T any departure from the normal in their contained radium, 

 nor was this found to be the case in those examined below. 



Schistose Metamorphosed Sediments (fine grained). 



Eock. 



Locality. Radium in grams per gram. 



Mica Slate 



Talc Slate 



Mica Schist 



Mica Schist 



Grey Schist 



Primitive Schistose | 

 Gneiss containing 

 Anhydrite. j 



Schiste Lustre 



Mica Schist (Calciferous) . 



Laurentiau Mica Schist ... 



Freybourg. 

 Delaware R. 

 Wicklow County. 

 Wexford County. 

 Oban. 



Simplon Tunnel. 



Simplon Tunnel. 

 Simplon Tunnel. 



1-7x10-12 gram. 



1-9 



1*4 



0-9 



06 



2-0 



05 



0-8 

 0-3 





Mean... \-\ X 10-12 gram. 



Specimens were examined also from some exposures near 

 Dublin of the actual contact of the Leinster Granite with its 

 overlying Silurian strata, to discover if possible any marked 

 effect due to the actual contact of the granite mass.' Sections 

 of the sedimentary rock cut both parallel and perpendicular 

 to the direction of compression from specimens taken from 



