8 REPORT — 1853. 



of the induced magnetism in the different substances for any inducing power of the 

 electro-magnet. All these curves will be very nearly represented by the equation 



M ^ I 

 — =: tan — , 

 c k 



M being the power of the magnet, I the intensity of the induced magnetism, and 

 Ic and c two constants varying from one substance to another. The curve will be 

 transformed into a straight line parallel to the axis when t)ie substance is saturated 

 •with magnetism ; it will be an inclined straight line when there is no resistance 

 against magnetization. Between these two straight lines are placed all our new 

 curves. 



The Professor deduced the following conclusions : — 



1. For every substance, either magnetic or diamagnetic, there is a particular law, 

 according to which the intensity of induced magnetism is determined by the inducing 

 power. 



2. There is for every substance a limit of magnetization, to which it approaches 

 more or less rapidly by increasing the power of the electro-magnet. 



3. The curves for diamagnetic bodies ascend very rapidly, much more rapidly 

 than the curve for iron does. By means of these curves we may find in what pro- 

 portion bismuth, for instance, is to be mixed with iron, so that the mixture may, 

 by a given power of the magnet, be neither attracted nor repelled. 



4. An eminent German philosopher explained all diamagnetic phsenomena by ad- 

 mitting that there is in diamagnetic substances no resistance to magnetization ; 

 but his theory cannot hold, the curves for bismuth and phosphorus ascending more 

 rapidly than the curves for most of the magnetic substances, but not so rapidly as 

 the curves for oxygen and hydrate of oxide of cobalt. The Professor was much 

 inclined to believe that all bodies retaining magnetism, as steel does, and, accord- 

 ing to his experiments, also oxygen, oppose a very small resistance against magnetiza- 

 tion. So may be explained in a more satisfactory way what has been improperly 

 called " coercive force." 



5. There is, generally speaking, no specific magnetism, as there is a specific 

 weight, a specific heat. The specific magnetism varies with the power inducing 

 it. Cobalt is more magnetic than iron when we make use of one of Grove's elements ; 

 but by giving to the current an intensity four times greater, the magnetism 

 of cobalt becomes only i^ths of that of iron. Let the magnetism of iron be one 

 million ; then by employing the stronger current and also the weaker one, the diamag- 

 netism of the bismuth will be in the first case 39, in the second 23"6 ; while 

 Professor Weber, making use of a much smaller inducing power, found only 10. So 

 we may also, partly at least, explain why Edm. Becquerel gives for the magnetism 

 of oxygen a number ten times less than Prof. Piiicker found, while his number agrees 

 pretty well with the approximate estimation of Dr. Faraday, who employed nearly the 

 same inducing power as he did. 



6. The Professor does not know what magnetism and diamagnetism are ; but the 

 curves for diamagnetic bodies being included on both sides by curves for magnetic 

 substances, he thinks there is no difference at all between the magnetic and diamag- 

 netic states of bodies, except that the conditions inducing these two states are oppo- 

 site ones. 



7. After having obtained his results, he was highly surprised by learning that a 

 French philosopher, Lallemand, had deduced from experiment the law according to 

 which the intensity of an induced current is dependent on the intensity of the in- 

 ducing one. He found for this case exactly the same law that Prof. Piiicker got for 

 magnetic induction. Though we do not know what an electric current really is, 

 by supposing that I.allemand's law and Pliicker's are true laws of nature, not merely 

 laws of approximation, we may conclude that magnetism and galvanism are one and 

 the same agency of nature. 



