M. De la Rive's Researches on the Voltaic Arc. SS5 



on the substance traversed by an interrupted current, and 

 that, consequently, magnetism has no more share in the phae- 

 nomenon than a finger might be supposed to have, when 

 pressing on a sonorous cord. The simple description of the 

 experiments shows this interpretation to be inadmissible. In 

 the first place, the sound is the same wit'fe the wires in a helix, 

 whether these wires be stretched or not, or whether they be 

 of lead, platinum, or brass. Besides, how could this account 

 for the sound produced in large masses, especially in liquids, 

 such as mercury, and for the fact, that the position of the 

 conductor traversed by the interrupted current with regard to 

 the poles of the electro-magnet does not exert any influence 

 on the phsenomenon? Further, it must be remarked that the 

 sound in question is not a musical sound, such as would be 

 produced by a string or mass made to vibrate by a cause acting 

 exteriorly at its surface; it is a series of sounds corresponding 

 exactly to the alternations of the passage of the current; like 

 a species of collision of the particles amongst themselves. 

 Thus, the phsenomenon is molecular; and it leads to the de- 

 monstration of two important principles. 



The first principle is, that the passage of the electric current 

 modifies, even in solid bodies, the arrangement of the par- 

 ticles ; a principle which I have already deduced from the ex- 

 periments contained in my preceding memoir on this subject. 

 The second principle is, that the action of magnetism, under 

 whatever form it may be exerted, modifies alike the molecular 

 constitution of all bodies, and that this modification lasts as 

 long as the cause producing it endures, and only ceases with 

 it. What is the nature of these two modifications ? This is 

 what we must endeavour to investigate and to ascertain. I pur- 

 pose to engage in this inquiry, and indeed I have already made 

 some attempts of which it would, however, be premature to 

 give any account. I shall confine myself at present to a single 

 remark, which does not appear to me to be devoid of interest : 

 it is, that the influence of magnetism on all conducting bodies 

 seems to impress on them, as long as it lasts, a molecular 

 constitution similar to that which iron, and generally all bodies 

 susceptible of magnetism possess naturally ; for it developes 

 in them the property of producing, when traversed by inter- 

 rupted currents, sounds identical with those emitted also by 

 iron and other magnetic bodies when transmitting these cur- 

 rents, but produced in these last without requiring the action 

 of a magnet. 



