THE 



LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



DECEMBER 1838. 



M' 



Llll. On the Galvanic Spark. By Prof. Dr. Jacobi. {Read 

 before the Imperial Academy of Sciences of St. Petersburg, 

 on the 27th of April 1838)*. 



R. FARADAY (Experimental Researches, art. 915.t) 

 regards as an essential support of the chemical theory 

 of the galvanic circuit, the galvanic spark, which is stated to 

 be obtained by a process, which he subsequently describes in 

 detail (art. 956. )> at the closing of a single galvanic circuit 

 " before contact of the different metals is made ; in fact at that 

 moment when chemical forces only are efficient as a cause of 

 action." In a subsequent series of his experimental re- 

 searches (1074.) Mr. Faraday does not, it is true, formally 

 retract this position, but he takes the opportunity of explain- 

 ing the phaenomena, which under certain circumstances are 

 exhibited on the closing of a galvanic circuit, in a different 

 manner, equally natural and ingenious. He observes, namely, 

 " The moment they (two metallic surfaces) come in contact, 

 the current passes, it heats, ignites, and even burns the touch- 

 ing points; and the appearance is as if the spark passed on 

 making contact, whereas it is only a case of ignition by the 

 current, contact being previously made, and is perfectly ana- 

 logous to the ignition of a fine platina wire connecting the 

 extremities of a voltaic battery |." Immediately after the dis- 

 covery of the so-called closing spark, I repeated these experi- 



* From the Bulletin Scientifique de fAcad. Imp. St. Petersbourg, T. iv. 

 No. 7- From a copy kindly communicated by the Author. Translated 

 by Mr. W. Francis. 



f Prof. Faraday's Eighth Series of Researches here referred to, will be 

 found in Lond. and Edinb. Phil. Mag., vol. vi. 



X This extract is from Prof. Faraday's Ninth Series, of which an abstract 

 will be found in L. &c E. Phil. Mag., vol. vi. p. 301 . 



Phil. Mag. S. 3. Vol. 13. No. 84% Dec. 1838. 2 D 



