﻿during the Formation of Graham's Hydrogenium. 425 

 the many astonishing discoveries made during the course of 

 these investigations, probably the most remarkable is the occlu- 

 sion of hydrogen by palladium. This metal, whether in the form 

 of sponge or hammered foil, when heated and cooled in an atmo- 

 sphere of hydrogen, absorbed between six and seven hundred 

 times its volume increasing to the enormous occlusion of 982 

 volumes when the metal used had been deposited by voltaic 

 action. This occlusion of hydrogen, Graham has shown, can be 

 easily effected a low temperatures by making palladium the 

 negative electrode during the electrolysis of water. He has 

 also shown that the metal charged with hydrogen increases 

 greatly in volume and that its physical properties are entirely 

 modified. So marked is the change in the physical, electrical 

 and magnetic properties of the combination, that the only class 

 of compounds we can compare it with are the metallic alloys. In 

 the occluded state the chemical intensity of hydrogen is increased 

 many reactions being effected by its agency beyond the powe of 

 the element in the free state. Graham, as a general result of hi 

 experiment, considers the occluded gas to exist in the form of 

 a solid, with all the physical properties of a metal. Durin<- the 

 course of an experimental exhibition of Graham's discovery I 

 noted several phenomena associated with the occlusion of hy- 

 drogen by palladium when it is made the negative electrode 

 during the electrolysis of water; and as they illustrate in a new 

 form the results already arrived at by the Master of the Mint 

 Soctt permlSS1 ° n I am induced t0 bl ' in S 't™ before the 



If a palladium plate, used as the negative electrode during the 

 decomposition of water be arranged at right angles instead of 

 parallel to a similar platmum plate, the hydrogen in a short 

 time „ evolved at the edge of the palladium plate nearest to the 

 painum electrode, no trace of hydrogen coming from any other 

 part of the plate. Gradually, as the saturation takes place, the 

 hydrogen seems to travel slowly along the plate, and only after 

 saturation is it freely evolved from the whole surface of the elec- 

 lll 11 j- W " no 7 1 revel ' se the cu "'ent, so as to evolve oxvgen at 

 the palladium plate, immediately the nearest edge begins to 

 evolve gas, the rest of the plate remaining tranquil ; "the evolution 

 of oxygen moves along the plate in a gradual manner. This 

 gradual transference depends on the time necessary to effect the 

 occlusion, and on the relative intensity of the lines of force 



When a palladium plate charged with hydrogen is brought 

 into contact with a platinum electrode freely evolving oxygen 

 evo ution of gas is immediately arrested over the entne surface 

 of the electrode. The same plate, free from hydrogen, when 

 brought into contactwith aplatmum electrode evolving tyWen 



