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XLIX. On the Universality of Magnetism. 

 By Dr. UE Haldat*. 



'^PHE question of the universality of magnetism, on which 

 -*- M. de Haldat presented a memoir to the Academy of 

 Sciences in ISllf, having given rise to some objections,"has 

 been subjected to new researches, in which the author has 

 confirmed the fact, that all bodies in small masses and of an 

 elongated form are subject to the influence of the magnet when 

 exposed to its action, both when they are made to oscillate 

 between the opposite magnetic poles, and when they are sus- 

 pended in the same situation by silk filaments whose torsion 

 is employed to value the force whicli they have acquired. A 

 desire to trace the proximate cause of these pheenomena in- 

 duced the author to ascertain whether these bodies possess, of 

 themselves, the property of acquiring the magnetic state, or 

 whether they owe this property to the presence of iron, as 

 many philosophers have maintained. 



It we consider magnetism in a general point of view, we 

 shall find that, to attribute this property to iron alone, is to 

 assign to that substance a special virtue, which later researches 

 have shown to exist in two other metals, and which the attrac- 

 tion of the magnetic needle by the rotatory discs composed 

 of various metals contradicts in the most direct manner; and 

 we must acknowledge that, in short, to deny to the fluid, the 

 magnetic agent, the generality of influence which we are forced 

 to recognise in the other agents, or imponderable fluids, as 

 heat, light and electricity, is to contravene the law of analogy, 

 which is one of our surest guides in the study of nature. How, 

 in fact, can we suppose that an agent which, like caloric, but 

 with an infinitely greater velocity, penetrates all bodies, can 

 be deprived of the property of exercising upon them an 

 influence analogous to that exerted by the other agents with 

 which it has such analogy? How can we admit, not only a 

 great resemblance but even an identity recognised by a great 

 number of philosophers between electricity and magnetism, and 

 deny the existence in one of its agents of that which we attri- 

 bute to the other? Finally, if all the agents, as is generally 

 believed, are only different modifications of one univeisal 

 agent, how can we deny to magnetism the generality of influ- 

 ence attributed to the fluid, the universal agent, of which it 

 would be, so to speak, one of the factors? 



These reasonings, conformable to the principles of natural 

 philosopl)y,and suilicient perhaps for philosophers who restrict 

 * From flic .innalcs de Chivde et de Physique, Jan. 1847. 

 t C'ompUt Jicndus det Hiancet de I' Acad, dcs Sciences, t. xii, p. 950. 



