r,r, Mr. W. Gannon. 



Hertz (H.) Electric Waves ; being Researches on the Propagation 

 of Electric Action with Finite Velocity through Space. 

 Authorised English Translation by D. E. Jones. 8vo. L<m<l >, 

 1893. Professor D. E. Jones. 



M ii-heli (M.) Alphonse de Candolle et son (Euvre Scientifique. 8vo. 

 ce 1893. The Author. 



Quatrefages de Breau (J. L. A. de) Notice Biographique. 4to. 

 [Private print.] Madame Quatrefages de Breau. 



Rodrigues (J. B.) Plantas Novas cnltivadas no Jardim Botanico do 

 Rio de Janeiro. No. 3. 4to. Itio de Janeiro 1893. 



The Author. 



Map of England and Wales showing Lines of Equal Magnetic 

 Declination for January 1, 1894. With a Reprint from the 

 ' Colliery Guardian.' Two copies. 



Mr. W. Ellis, F.R.S., and The Editor, ' Colliery Guardian.' 



* On Copper Electrolysis in Focuo." By WILLIAM GAXXOX, 

 M.A., "1851 Exhibition" Scholar, Queen's College, 

 Galway. Communicated by ARTHUR SCHUSTER, F.R.S. 

 Received November 14, Read December 7, 1893. 



The following research upon the electrolysis of copper sulphate in 

 'iC7to was commenced nearly two years ago, at the suggestion of 

 Dr. Schuster, and the experiments were made in the Physical 

 Laboratory of the Owens College. 



The electrolysis of copper salts is interesting, not only theoretically 

 :is affording a verification of Faraday's Law of Electrolytes, but also 

 practically on account of its constant use in the graduation of current- 

 measuring instruments, such as tangent galvanometers and ammeters. 

 It is known that copper sulphate in solution does not conform 

 rigorously to the simple form in which Faraday's law is generally 

 expressed. Gray,* who made a detailed examination of the electrolysis 

 of copper sulphate, found that the weight of the deposit is very 

 variable in neutral solutions for the same current and the same 

 interval of time; and he also showed that, in solutions containing a 

 little free sulphuric acid, this inconstancy was removed, but that the 

 weight was a function of the temperature of the solution and of the 

 current density at the cathode. His results with acid solutions are 

 graphically represented by curves (partly reproduced at the end of 



' Phil. Mag.,' vola. 22 and 25 (1886-88). 



