* ON LIVING MALAPTERURUS. 391 



laid down as the first principle of the science of electricity, the 

 identity of all electricity, whatever be its origin ; but as regards 

 the five electricities Voltaic, friction, magneto-, thermo-, and 

 animal electricity in enumerating the eight effects which ought 

 to be obtained in order to prove their identity, Faraday was com- 

 pelled in the case of animal electricity to leave four blanks, viz., the 

 spark, thermic effect, attraction and repulsion, and conduction 

 through hot air 1 . Since then, the three first of these effects have 

 been obtained in the Torpedo, and in part by Faraday himself, in 

 the Gymnotus, and the whole position of the matter is such that no 

 one would seriously doubt that the electricity of the Malapterurus 

 is also ordinary electricity. I thought, nevertheless, that I ought 

 not to let the opportunity slip, to complete Faraday's table as far as 

 possible for this fish also. A part of the experiments to be described 

 were made with simple metal saddles, and not with the leading-off 

 cover. As they would have been completely successful with the 

 covers, I have not needlessly hampered the description of them by 

 an account of the mode of leading-off used each time. 



i. Electrolysis. 



The physiological effect and the deflection of the magnetic needle 

 have been already spoken of. Concerning electrolysis, I first 

 observed, with aid of the frog - interrupter, polarisation of the 

 electrodes by the shock of Malapterurus. This observation is so far 

 of importance, as it enabled me to dispense with the decomposition 

 of water, which latter has been unsuccessful in my hands, if indeed 

 it has succeeded in any other 2 . 



In the electrolysis of iodide of potassium, the remarkable cir- 

 cumstance presented itself, which must have been overlooked by 

 observers of the Torpedo and Gymnotus, that a patch appeared under 

 each point. The two effects, polarisation and secondary iodine 

 patch, which are so closely connected together, were made by me 

 the subject of a special investigation which will be found in the 

 following paper. It was here particularly that the frog-interrupter 

 rendered me help which could scarcely otherwise have been obtained. 



In order to observe the decomposition of water, I enclosed two 



1 Experimental Eesearches, etc., vol. i. London, 1839, P- 99 S( 1- Series III, 1883, 

 35 1 sq. 



2 John Davy states that he decomposed water with gold and platinum wires 

 (Kesearches, physiological and anatomical, etc., vol. i. p. 15), Saint-Linari with iron 

 wires (Bibliotheque universelle de Geneve, 1837, * v ^- P- 395)- 



