332 WHARTON — PALLADIUM (Pd). [April 7, 



PALLADIUM (Pd). 



BY JOSEPH WHARTON, Sq-D., LL.D. 



(Bead April 7, 1904.) 



Although palladium belongs to the platinum group of metals, it 

 is in some respects nearly related also to silver, its atomic weight and 

 specific gravity being respectively about 107 and 1 1.4, while the 

 corresponding figures for silver are 108 and 10.5. In its high 

 melting point, however, of 1500° C, it approaches more nearly tO' 

 platinum which melts at 1750° C, and in color its grayish-white 

 resembles the color of platinum more nearly than that of silver. 



Palladium has long been known to occur native in company with 

 platinum, and also alloyed with gold in the Brazilian mineral por- 

 pezite which contains about 5 to 10 per cent, of it. That it occurs 

 in notable quantity in the nickeliferous pyrrhotite of Canada is an 

 important recent observation. 



Both platinum and palladium probably exist to a greater or less 

 extent in all the many deposits of nickeliferous pyrrhotite through- 

 out the world ; certainly in those of Norway and Sweden, and par- 

 ticularly in every one of the numerous deposits of that mineral 

 which are found in the Laurentian and Huronian rocks surrounding 

 the little town Sudbury, in the province of Ontario, Canada. The 

 quantity, however, is extremely small, varying from a mere trace to- 

 one or more ounces per ton ; the average for each metal being 

 about one-hundredth of an ounce per ton of ore, platinum and 

 palladium usually being present in approximately equal parts. 



Yet, though known to exist in many parts of the world, palladium 

 has not been diligently sought for, because there was until recently 

 no considerable demand for it ; the reworking of platiniferous resi- 

 dues from the mints of several countries having supplied most of 

 that which appeared in commerce. The prevailing scarcity of 

 platinum is now directing attention to palladium as a practicable 

 substitute for some purposes. 



The nickeliferous pyrrhotite deposits of the Sudbury region 

 have recently become the most important source of nickel in the 

 world and appear certain to continue so for many years, having quite 

 surpassed in yield the great nickel-silicate ores of New Caledonia 

 which come next in rank. In these Canadian ores, silver, gold, 

 platinum, iridium and rhodium occur as well as palladium ; all in 

 very minute quantities — palladium as above mentioned to the 

 extent of about .01 oz. per ton. 



