On the Electric Conducting Power of Mercury. 



171 



cases, as in that of the Oural, incorporating them into the body 

 of the new continent, but in others leaving them in the form of 

 peninsulas extending north and south, as in the case of South 

 America, or of insulated tracts, as in the case of Australia. 



The following are the (known) important axes which governed 

 the geographical configuration of the secondary period; the 

 letters refer to the diagram below. Axes such as the Jura, 

 which came into existence very late in the secondary period, 

 and whose influence npon this configuration was but subordi- 

 nate, or as the principal axis of the Pyrenees, which, although 

 of secondary origin, preceded only the newer cretaceous epoch, 

 and whose influence is rather to be considered among those to 

 be discussed in the 3rd section as governing the post-cretaceous 

 configuration, are omitted in this list and diagram. 



Direction. 



Chain of Oural 



Chain of Andes 



Chain of Rocky Mountains . . 



Chain of Alleghanies .... 

 e. System of England and Portugal. 

 /. System of Eastern Australia . . 



N. to S. 



N. to S. 



N.N.W. to S.S.E. 



N.E. to S.W. 



N. by W. to S. by E. 



N. byE.toS. byW. 



[To be continued.] 



XXIV. On the Influence of Traces of Foreign Metals on the 

 Electric Conducting Power of Mercury. By A. Matthiessen, 

 F.R.S.; and C. Vogt, Ph.D * 



TTlHE fact that mercury, when alloyed with traces of foreign 



_L metals, shows an increment, and not, as most pure metals, 



* Communicated by the Authors. 



