382 Mr. J. P. Marrian on So?iorous 



are not yet sufficiently numerous to allow of my venturing 

 upon a description of them in this paper. 



It is evident, therefore, that the cyanide of potassium and 

 silver in a neutral state is a most excellent conductor of elec- 

 tricity. A little cyanide of potassium added does however 

 facilitate its decomposition; and it is remarkable that when 

 the cyanide of potassium added is in such proportion as to 

 form a compound having two equivalents of cyanide of potas- 

 sium to one of cyanide of silver, it is probably the most easily 

 decomposed substance that we have. I have deposited silver 

 from it easily with one square inch of copper and zinc im- 

 mersed in water, the solution being at a temperature of 75°. 



Another question suggested itself in connection with this 

 salt, namely, the manner in which the cyanogen is transferred 

 from the negative to the positive electrode, whether it travels 

 direct, or is transmitted from particle to particle. Probably 

 this has been answei-ed satisfactorily long ago by other experi- 

 menters; but this being a salt eminently fitted to determine 

 this question, I made the following experiment: — Into one 

 division of the decomposition cell, a solution of pure cyanide 

 of potassium and silver was introduced, and into the other 

 division a neutral solution of chloride of potassium. By this 

 arrangement, I considered that, if the cyanogen travelled di- 

 rect, cyanide of silver should be formed upon the positive 

 electrode which was immersed in the chloride of potassium ; 

 and if it was transmitted from particle to particle, chloride 

 of silver would be deposited upon the pole and cyanide of 

 potassium formed in the solution. The experiment verified 

 this last supposition ; after a current had passed through the 

 solution for nearly eight hours the positive electrode was com- 

 pletely encased in a horny crust of considerable flexibility, 

 which was not soluble in strong boiling nitric acid nor in hot 

 sulphuric acid, and did not give off' fumes of hydrocyanic acid 

 on the addition of muriatic acid. 25 grains gave 18'6 of 

 silver, which with the previous experiments is sufficient to 

 prove the substance to be chloride of silver; the solution had 

 the smell of cyanide of potassium, which had dissolved or de- 

 composed a portion of the chloride of silver it held in solution. 



LXVI. Oti Sonorojis Phenomena in Electro- Magnets. 



By J. P. Marrian. 



To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 



TJTAVING noticed a fevi phsenomena resulting from mag- 



*■ netic influence in bars of soft iron, and which I have 



not before heard of, I am induced to submit an account of 



