234 Dr. Faraday on Magnetic and Diamagnetic Action. 
it does not tend to move, and is then in marked contradistinetion 
with a linear current of electricity under the same circumstances. 
2419, This condition and effect is new, not only as it respects 
the exertion of power by a magnet over bodies previously sup- 
posed to be indifferent to its influence, but is mew as a magnetic 
action, presenting us with a second mode in which the magnetic 
power can exert. its influence. - These two modes are in the same 
general antithetical relation to each other as positive and negative 
in electricity, or as northness and southness in polarity, or as the 
lines of electric and magnetic force in magneto-electricity ; and 
the diamagnetic phenomena are the more important, because they 
extend largely, and in a new direction, that character of duality 
which the magnetic force already, in a certain degree, was known 
to possess. 
2420. All matter appears to be subject. to the magnetic force 
as universally as it is to the gravitating, the electric, and the | 
chemical or cohesive forces; for that which is not effected by it 
in the manner of ordinary magnetic action, is effected in the 
manner I have now described ; the matter possessing for the time 
the solid or fluid state. Hence substances appear to arrange 
themselves into two great divisions, the magnetic, and that which 
I have called the diamagnetic classes; and between these classes 
the contrast is so great and direct, though varying in degree, that 
where a substance from the one class will be attracted, a body 
from the other will be repelled; and where a bar of the one will 
assume a certain position, a bar of the other will: — a poe 
tion‘at right angles to it. 
2421. As yet I have not tated a single solid or fluid body not 
being a mixture, that is perfectly neutral in relation to the two 
lists; i. e. that is neither attracted nor repelled in air. It would 
probably be important to the consideration of magnetic action, 
to know if there were any natural simple substance possessing 
this condition in the solid or fluid-state. Of compound or-mixed 
bodies there may be many; and as it may be important to the 
advancement of experimental investigation, I will describe the 
principles on which such a substance was prepared when required - 
for use as a circumambient medium. 
_ 2422. It is manifest that the properties of magnetic and dine 
magnetic bodies are in opposition as respects their dynamic ef- 
ects 5 acai ‘cea! that by a Sneeixiee of bodies from each 
