48 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXI.) 
Specimens of the metal from Mr. Johnson, considered as pure, were also slightly 
magnetic. The chloride, the ammonio-bichloride, and the cyanuret of palladium, 
pointed equatorially and were repelled by the magnet. The same cyanuret, reduced 
by heat either in open platinum vessels or in close glass tubes, gave palladium possess- 
ing a feeble degree of magnetic property. Some of Wollaston’s palladium was 
dissolved in pure nitromuriatic acid, and the solution slowly acted upon by pure 
zinc, free from iron, and not magnetic. Five successive portions of the precipitated 
metal were collected, and all were magnetic. Ammonio-bichloride of palladium was 
prepared from the same solution by pure acid muriate of ammonia, and digested in 
nitromuriatic acid. The salt itself was repelled, being diamagnetic ; but when 
reduced by heat in glass tubes, or in Berlin capsules, the palladium obtained was 
magnetic. From the result of all the experiments, I believe the metal to be feebly 
but truly magnetic. 
2383. Arsenic . — This metal required very particular examination, and even when 
carefully sublimed twice or thrice in succession, presented appearances which some- 
times made me class it with the magnetic, and at other times with the diamagnetic 
bodies. On the whole, I incline to believe that it belongs to the latter series of sub- 
stances, being only in a very small degree removed from the zero or medium point. 
Pure white arsenic points freely in an equatorial direction, and is repelled by a mag- 
netic pole. 
2384. In reference to the pointing of short bars between magnetic poles exposing 
large flat faces, I ought to observe, that such bars will sometimes point axially and 
seem to be magnetic when they do not belong to that class, and are repelled by a 
single pole. The cause of this effect has been already given (2298. 2299.), and is 
obviated by the use of poles having wedge-shaped or conical terminations. 
2385. Osmium . — Osmic acid from Mr. Johnson, in fine transparent crystals, was 
clearly diamagnetic, being repelled. Specimens of the metal and of the protoxide 
were both slightly magnetic. The protoxide had been obtained by the action of 
alcohol on a solution of osmic acid which had twice been distilled with water, and 
the metal was believed to be perfectly free from other substances. Probably, there- 
fore, osmium belongs to the magnetic class. 
2386. Iridium. — Mr. Johnson supplied me with several preparations of iridium. 
The oxide, chloride, and ammonio-chloride were magnetic ; and so was a sample of 
the metal. One specimen of the metal, which seemed to be very pure, was scarcely 
at all magnetic ; and on the whole, I incline to believe that iridium does not stand in 
the magnetic class. 
2387- Rhodium. — A well-fused specimen of this metal, prepared by Dr. Wollaston, 
was magnetic ; but crystals of the chloride and the sodio-chloride of rhodium pre- 
pared by the same philosopher, and others also from Mr. Johnson, were not magnetic, 
but pointed well equatorially. I conclude, therefore, that the metal is probably not 
magnetic, or if magnetic, is but little removed from the zero point. 
