some Igneous Rocks from Antarctic Regions. 



771 



before sufficient acidification, suggests possibilities when 

 traces of radium emanation are sought for in bulky and 

 chemically rich solutions — especially those which are examined 

 in the alkaline state. 



The following: results were obtained : — 









Radium 



Thorium 



Radium 



To, 



Rock. 



Locality. 



gr. per gr. 



gr. per gr. 



Thorium 



1 



Basalt 



Mt. Erebus, McMurds Sound 



Mt. Erebus, Ross Sound 



2-13 Xl0" 12 



2-17 „ 



1-45X 10" 

 145 „ 



1-5X10- 7 

 1-5 „ 



<-■> 



Kenyt lava 



8 



Alkali trachyte ... 



Traohytic 1 

 doleritic kenyt J 



Mt. Erebus (South cliffs) 



2-16 



1-30 „ 



1-6 „ 



4. 





1-3 „ 



0-8 „ 



1*6 „ 







5 



Kenvt lava 



Cape Royds, Ross Sound 



1-46 



07 „ 



2-0 „ 



6. 



7. 



Kenyt (coloured 1 

 red by geyser I 

 action. J 



Vesicular basic 1 

 lava J 



McMurds Sound, Ross Sound 



McMurds Sound, Ross Sound 



4-02 „ 

 0-58 „ 



1-84 „ 

 0-47 „ 



2*2 

 1"2 „ 



8. 



Olivine augite ^ 

 basalt. / 



McMurds Sound, Ross Sound 



0-38 „ ? 



(H8 „ 



0-8 „ ? 



9. 



Olivine felspar "1 



basalt. J 

 Hornblende 1 



basalt. J 

 Erratic granite 1 



block. ] 

 Erratic granite | 



block. ) 

 Erratic granite ) 



block. 

 Another variety. J 



Cape Royds, Ross Sound 



o-oo ? 



040 





LO. 



Cape Barn, Ross Sound 



0-47 ? 



1-00 



0*5 ? 



LI. 



Cape Royds, Ross Sound 



0*82 9 



0o3 , 



1-5 



.2. 



McMurds Sound, Ross Sound 



0-70 „ 



0-37 „ 



1-9 „ 



L3. 



" Lower ground " of S. Victoria-land 



0-20 „ 



044 „ 



1-4 „ 





Mean ( e " 

 L quer 



eluding 1 

 ied results J 



17 



* For description of rock-type see Quart. Journ. Geol. Soc. Lond. 1900, 

 vol. lvi. p. 209. 



One of the most noticeable features of the above results is 

 the remarkable constancy obtaining in the case of both 

 radium and thorium among specimens from the same locality, 

 and probably taking their origin from a common magma. 

 This feature, which is as much marked in the case of the 

 thorium as in that of the radium, seems to be independent 

 of the basicity or acidity of the rock. Thus in the case oi' 

 Nos. 1, 2, and 3 in the above table, the figures are. within 

 the limits of experimental error, identical, yet the rocks, 

 although all from Mt. Erebus, are by no means similar 



