﻿Hydrogen to Palladium. 129 



itself at vest. The gas being afterwards extracted, and the pal- 

 ladium again placed equatorially between the poles, it was not 

 deflected in the least perceptible degree. The addition of hy- 

 drogen adds manifestly, therefore, to the small natural magnetism 

 of the palladium. To have some terms of comparison, the same 

 little mass of electro-deposited palladium was steeped in a solu- 

 tion of nickel, of specific gravity 1*082, which is known to be 

 magnetic. The deflection under the magnet was now 35°, or 

 less than with hydrogen. The same palladium being afterwards 

 washed and impregnated with a solution of protosulphate of iron 

 of specific gravity T018, of which the metallic mass held 23 per 

 cent, of its weight, the palladium gave a deflection of 50°, or 

 nearly the same as with hydrogen. With a stronger solution of 

 the same salt, of specific gravity IT 7, the deflection was 90°, 

 and the palladium pointed axially. 



Palladium in the form of wire or foil gave no deflection when 

 placed in the same apparatus, of which the moderate sensitiveness 

 was rather an advantage in present circumstances ; but when 

 afterwards charged with hydrogen, the palladium uniformly gave 

 a sensible deflection of about 20°. A previous washing of the 

 wire or foil with hydrochloric acid, to remove any possible traces 

 of iron, did not modify this result. Palladium reduced from the 

 cyanide and also precipitated by hypophosphorous acid, when 

 placed in a small glass tube, was found to be not sensibly mag- 

 netic by our test; but it always acquired a sensible magnetism 

 when charged with hydrogen. 



It appears to follow that hydrogenium is magnetic, a property 

 which is confined to metals and their compounds. This mag- 

 netism is not perceptible in hydrogen gas, which was placed 

 both by Faraday and by M. E. Becquerel at the bottom of the 

 list of diamagnetic substances. This gas is allowed to be upon 

 the turning-point between the paramagnetic and diamagnetic 

 classes. But magnetism is so liable to extinction under the in- 

 fluence of heat, that the magnetism of a metal may very possibly 

 disappear entirely when it is fused or vaporized, as appears with 

 hydrogen in the form of gas. As palladium stands high in the 

 series of the paramagnetic metals, hydrogenium must be allowed 

 to rise out of that class, and to take place in the strictly mag- 

 netic group, with iron, nickel, cobalt, chromium, and man- 

 ganese. 



Palladium with Hydrogen at a high Temperature. — The ready 

 permeability of heated palladium by hydrogen gas would imply 

 the retention of the latter element by the metal even at a bright 

 red heat. The hydrogenium must in fact travel through the 

 palladium by cementation, a molecular process which requires 

 time. The first attempts to arrest hydrogen in its passage 



Phil. Mag. S. 4. Vol. 37. No. 247. Feb. 1869. K 



