C 41 ] 
III. Experimental Researches in Electricity . — Twenty-first Series. 
By Michael Faraday, Esq., D.C.L., F.R.S., Fullerian Prof. Chem. Royal Insti- 
tution, Foreign Associate of the Acad. Sciences, Paris, Cor. Memh. Royal and 
Imp. Acadd. of Sciences, Petershurgli, Florence, Copenhagen, Berlin, Gottingen, 
Modena, Stockholm, fyc. 8$c. 
Received December 24, 1845, — Read January 8, 1846. 
^ 27 . On new magnetic actions, and on the magnetic condition of all matte 1 — continued. 
v. Action of magnets on the magnetic metals and their compounds. vi. Action 
of magnets on air and gases. vii. General considerations. 
v. Action of magnets on the magnetic metals and their compounds. 
2343. THE magnetic characters of iron, nickel and cobalt, are well known ; and 
also the fact that at certain temperatures they lose their usual property and become, 
to ordinary test and observation, non-magnetic ; then entering into the list of dia- 
magnetic bodies and acting in like manner with them. Closer investigation, how- 
ever, has shown me that they are still very different to other bodies, and that though 
inactive when hot, on common magnets or to common tests, they are not so abso- 
lutely, but retain a certain amount of magnetic power whatever their temperature ; 
and also that this power is the same in character with that which they ordinarily 
possess. 
2344. A piece of iron wire, about one inch long and 0’05 of an inch in diameter, 
being thoroughly cleaned, was suspended at the middle by a fine platinum wire con- 
nected with the suspending thread (2249.) so as to swing between the poles of the 
electro-magnet. The heat of a spirit-lamp was applied to it, and it soon acquired a 
temperature which rendered it quite insensible to the presence of a good ordinary 
magnet, however closely it was approached to the heated iron. The temperature of 
the iron was then raised considerably higher by adjustment of the flame, and the 
electro- magnet thrown into action. Immediately the hot iron became magnetic and 
pointed between the poles. The power was feeble, and in this respect the state of 
the iron was in striking contrast with that which it had when cold ; but in character 
the force was precisely the same. 
2345. The iron was then allowed to fall in temperature slowly so that its assump- 
tion of the higher magnetic condition might be observed. The intensity of the force 
did not appear to increase until the temperature arrived near a certain point, and 
MDCCCXLVI. G 
