54 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXI.) 
could be made to pass more and more into the magnetic or the diamagnetic class by 
the addition of more sulphate of iron or more water. 
2423. Thus a fluid medium was obtained, which, practically, as far as I could per- 
ceive, had every magnetic character and effect of a gas, and even of a vacuum ; and 
as we possess both magnetic and diamagnetic glass (2354.), it is evidently possible to 
prepare a solid substance possessing the same neutral magnetic character. 
2424. The endeavour to form a general list of substances in the present imperfect 
state of our knowledge would be very premature: the one below is given therefore 
only for the purpose of conveying an idea of the singular association under which 
bodies come in relation to magnetic force, and for the purpose of general reference 
hereafter : — 
Iron. 
Nickel. 
Cobalt. 
Manganese. 
Palladium. 
Crown-glass. 
Platinum. 
Osmium. 
0° Air and vacuum. 
Arsenic. 
Ether. 
Alcohol. 
Gold. 
Water. 
Mercury. 
Flint-glass. 
Tin. 
Heavy glass. 
Antimony. 
Phosphorus. 
Bismuth. 
2425. It is very interesting to observe that metals are the substances which stand 
at the extremities of the list, being of all bodies those which are most powerfully op- 
posed to each other in their magnetic condition. It is also a very remarkable cir- 
cumstance that these differences and departures from the medium condition, are in 
the metals at the two extremes, iron and bismuth, associated with a small conducting 
power for electricity. At the same time the contrast between these metals, as to their 
fibrous and granular state, their malleable and brittle character, will press upon the 
mind whilst contemplating the possible condition of their molecules when subjected 
to magnetic force. 
