270 Chronicles of Science. L^^P^'^^j 



5. CHEMISTRY. 



AYiTHOUT exce2')tion, the most important contribution to chemical 

 science which has been pubhshcd for some time is the paper 

 recently read by Professor Graham, the Master of the Mint, on 

 Hydrogeninm. The author discovered some time ago that the 

 metal palladium was capable of absorbing, or occluding, as he 

 terms it, 800 or 900 times its volume of hydrogen; and the idea 

 has forced itself upon his mind, that palladium with its occluded 

 hydrogen was simply an alloy of a volatile metal hydrogen, in which 

 the volatility of the one element is restrained by its union with the 

 other, and which owes its metallic aspect equally to both con- 

 stituents. How far such a view is borne out by the properties of 

 the compound substance in question, will appear by the following 

 examination of the properties of what, assuming its metalhc cha- 

 racter, may be named hydrogenium:^ 



The density of palladium when charged with 800 or 900 times 

 its volume of hydrogen gas is perceptibly lowered, being reduced 

 from 12"3 to 11*79; and, ultimately, as the mean of several con- 

 cordant experiments, the density of hydrogenium was found to be 

 1-951, or nearly 2. 



The tenacity of the hydrogen-charged wire was found to be 

 81-29, that of the original palladium wire being 100. It is seen, 

 therefore, that the tenacity of the palladium is reduced by the 

 addition of hydrogen, but not to any great extent. It is a question 

 whether the degree of tenacity that still remains is reconcilable 

 with any view other than that the second element present possesses 

 of itself a degree of tenacity such as is only found in metals. 



The electric conductivity was tested by submitting a palladium 

 wire before and after charging with hydrogen to trial, in comparison 

 with a wire of gcrman silver of equal diameter and length, at 10-5^. 

 The conducting power of the several wires was found as follows, 

 being referred to pure copper as 100 : — • 



ralludium 8-10 



Palladium + hydrogen 5-99 



A reduced conducting power is generally observed in alloys, 

 and the charged palladium wire foils 25 per cent. But the con- 

 ducting power remains still considerable, and the result may bo 

 construed to favour the metallic character of the second constituent 

 of the wire. As regards magnetism it was found that the addition 

 of hydrogen to palladium added manifestly to the small natural 

 magnetism of palladium. It follows, therefore, that hydrogenium 

 is magnetic, a property which is confined to metals and their 

 compounds. This magnetism is not perceptible in hydrogen gas. 



