50 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXI.) 
Magnetic. 
Diamagnetic. 
Bismuth. 
Antimonv. 
Zinc. 
Tin. 
Cadmium. 
Sodium. 
Iron. 
Mercury. 
Nickel. 
Lead. 
Cobalt. 
Silver. 
Manganese. 
Copper. 
Chromium. 
Gold. 
Cerium. 
Arsenic. 
Titanium. 
Uranium. 
Palladium. 
Rhodium. 
Platinum. 
Iridium. 
Osmium. 
Tungsten. 
i 
1 
vi. Action of magnets on air and gases. 
2400. It was impossible to advance in an experimental investigation of the kind 
now described, without having' the mind impressed with various theoretical views of 
the mode of action of the bodies producing 1 the phenomena. In the passing con- 
sideration of these views, the apparently middle condition which air held between 
magnetic and diamagnetic substances was of the utmost interest, and led to many 
experiments upon its probable influence, which I will now proceed briefly to describe. 
2401. A thin flint-glass tube, in which common air was hermetically enclosed, was 
placed between the magnetic poles (2249.) surrounded by air, and the effect of the 
magnetic force observed upon it. There was a very feeble tendency of the tube to 
an equatorial position, due to the substance of the tube in which the air was 
enclosed. 
2402. The air was then withdrawn from around the tube more or less, and at last 
up to the highest amount which a good air-pump would effect ; but whatever the 
degree of rarefaction, the tube of air still seemed to be affected exactly in the same 
manner as if surrounded by air of its own density. 
2403. I then surrounded the air-tube with hydrogen and carbonic acid in succes- 
sion ; but in both these, and in each of them at different degrees of rarefaction, the 
tube of air remained as indifferent as before. 
2404. Hence there appears to be no sensible distinction between dense or rare air ; 
or, as far as these experiments go, between one gas or vapour and another. 
2405. As it did not seem at all unlikely that the equatorial and axial set of bodies, 
