708 



Notices respecting New Books. 

 Table IV. 



Depth in cms. 



Current : 



Arbitrary Scale. 



00 



21-1 



150 



20 5 



600 



18-0 



77-0 



17-0 



97-0 



143 



1100 



13-75 



1200 



133 



The experiment was repeated with the cylinder placed in a 

 tank 50 cms. in diameter. This tank permitted the cylinder 

 to be surrounded by a layer of water 12 '5 cms. in thickness, 

 and it was found when the water was poured in that the con- 

 ductivity fell off 17 '5 per cent. 



From these results it is evident that the ordinary air of a 

 room is traversed by an exceedingly penetrating radiation, 

 such as that which Rutherford* has shown to be emitted by 

 thorium, radium, and the excited radioactivity produced by 

 thorium and radium. 



In order, therefore, to reach definite conclusions regarding 

 the extent and true character of the effect of various metals 

 upon the conductivity of die air which they inclose, it will 

 be necessary to entirely cut off the inclosing vessel from the 

 action, of this external radiation, and the writers have not yet 

 carried their experiments to this point. 



Physical Laboratory, 



University of Toronto. 



LXXVIII. Notices respecting New Books. 

 Text-Book of Electrochemistry. By Svante Arehenius, Professor 



at the University of Stockholm. Translated by John McCbae, 



Ph.D. London: Longmans, Green, & Co., 1902. Pp. xii-f- 



344. 

 TN the English edition of this text-book by one of the leading 

 -*- authorities on electrochemistry, we find much to praise and not a 

 little to blame. We shall probably best discharge our duties towards 

 the author and the translator by stating that no one interested in 

 the subject can afford to ignore the book, written as it is by one 

 whose name will ever remain associated with the epoch-making 

 theory of ionization. 



Having said so much, we think that both the translators and the 

 reader's interests will be best served if we draw attention to some of 



Rutherford, 'Nature/ vol. lxvi. p. 318 (1902). 



