Dec. 1845.] On new Magnetic Actions. 397 



ledge) had been impressed on matter by subjecting it to the 

 action of magnetic and electric forces (2227.) ; which new 

 condition was made manifest by the powers of action which 

 the matter had acquired over light. The phaenomena now to 

 be described are altogether different in their nature : and they 

 prove, not only a magnetic condition of the substances referred 

 to unknown to us before, but also of many others, including 

 a vast number of opake and metallic bodies, and perhaps all 

 except the magnetic metals and their compounds : and they 

 also, through that condition, present us with the means of 

 undertaking the correlation of magnetic phaenomena, and 

 perhaps the construction of a theory of general magnetic ac- 

 tion founded on simple fundamental principles. 



2244. The whole matter is so new, and the phaenomena so 

 varied and general, that I must, with every desire to be brief, 

 describe much which at last will be found to concentrate under 

 simple principles of action. Still, in the present state of our 

 knowledge, such is the only method by which I can make 

 these principles and their results sufficiently manifest. 



% i. Apparatus required. 



2245. The effects to be described require magnetic apparatus 

 of great power, and under perfect command. Both these 

 points are obtained by the use of electro-magnets, which can 

 be raised to a degree of force far beyond that of natural or 



soft iron, on the deutoxide and tritoxide of iron, on the tritoxide alone, 

 and on a needle of wood. The author observed, and quotes Coulomb as 

 having also observed, that a needle of wood, under certain conditions, 

 pointed across the magnetic curves; and he also states the striking fact 

 that he had found a needle of wood place itself parallel to the wires of a 

 galvanometer. These effects, however, he refers to a degree of magnetism 

 less than that of the tritoxide of iron, but the same in character, for the 

 bodies take the same position. The polarity of steel and iron is stated to 

 be in the direction of the length of the substance, but that of tritoxide of 

 iron, wood and gum-lac, most frequently in the direction of the width, and 

 always when one magnetic pole is employed. " This difference of effect, 

 which establishes a line of demarcation between these two species of phe- 

 nomena, is due to this, that the magnetism being very feeble in the tritox- 

 ide of iron, wood, &c, we may neglect the reaction of the body on itself, 

 and therefore the direct action of the bar ought to overrule it." 



As the paper does not refer the phenomena of wood and gum-lac to an 

 elementary repulsive action, nor show that they are common to an immense 

 class of bodies, nor distinguish.this class, which I have called diamagnetie, 

 from the magnetic class ; and, as it makes all magnetic action of one kind, 

 whereas I show that there are two kinds of such action, as distinct from 

 each other as positive and negative electric action are in their way, so I do 

 not think I need alter a word or the date of that which I have written ; but 

 am most glad here to acknowledge M. Becquerel's important facts and la- 

 bours in reference to this subject. — M. F. Dec. 5, 1845. 



