CHEMISTRY. 195 



The property of occluding hydrogen belongs also to tlie alloys 

 of jxalladium when the second metal does not form more than 

 one-half the alloy. In this case the expansion is about twice as 

 great as in the case of pure palladium, and on expelling the hy- 

 drogen the alloy returns to its original dimensions without further 

 retraction. The density of h3'drogenium, calculated from a series 

 of experiments with alloys of palladium, gave results between 

 0.711 and 0.755, the mean of which would be 0.733. 



Tenacity. — The tenaqity of the alloy of palladium and hydro- 

 genium is less than that of palladium. If the tenacity of the lat- 

 ter be represented by 100, that of the alloy will be represented by 

 81.29. 



Conductivity. — The electric conductivity of copper being rep- 

 resented by 100, that of ])alladium would be represented by 8.10, 

 and that of the alloy by 5.99. 



The conductivity, although diminished, still remains consider- 

 able, which would show the metallic character of hydrogenium. 



Magnetism. — Palladium is feebly but truly magnetic; the alloy 

 is magnetic to a greater degree, which fact indicates the metallic 

 character of the other component of the alloy. 



Chemical Characters. — The chemical properties of hydroge- 

 nium also distinguish it from ordinary hydrogen: e. g., the 

 palladium alloy precipitates mercury and calomel from a solu- 

 tion of mercuric chloride without disengagement of hydrogen; 

 that is, hydrogenium decomposes mercuric chloride while hy- 

 drogen does not. 



The conclusions arrived at are, that hydrogenium is a white 

 solid of metallic aspect, of a density between 7 and 8, and ca- 

 pable of forming with an equivalent proportion of palladium a 

 delinite alloy. 



CELL-STRUCTURE OF METALS. 



A paper, by W. Vivian, recently read before the Liverpool 

 Polytechnic Society, presented some interesting points in regard 

 to the microscopic structure of metals. Mr. Vivian classes met- 

 als under two heads, narael}^ those the structure of which is an- 

 gular or crystalline, and those in which it is cellular or porous. 

 The cellular structure is most highly developed in those metals 

 which we have found to be the best conductors of heat and elec- 

 tricity ; audits perfection is in proportion to the capacity for such 

 conduction. " The ' fibre,' or ' silky lustre,' exhibited in the 

 fracture of good iron," says Mr. V.,'*is only the elFect of the 

 light reflected from the innersurfaces of myriads of minute cells ex- 

 posed by the fracture. The form of these;, in their normal state, 

 is spherical, or nearly so, but becomes changed in the process of 

 rolling. The mechanical properties of tenacity, ductility, etc., 

 must greatly depend on the perfection of the cell system ; a 

 crystalline, malleable iron does not show prisms in its fracture, but 

 simply a number of faces or x>lanes crossing the cells at right 

 angles, cutting them off short. The process of rolling iron into 



