RARE METALS FROM OLD COINS.
The operations of the Government assay office in Frankfort during the last year have developed the fact that gold, platinum, palladium, and selenium are found in old silver coins and also in ores which were formerly supposed to be nearly pure sulphides and oxides of lead and silver. From 400,000 pounds of silver and 5,000 pounds of gold were obtained twelve pounds of platinum, two pounds of palladium, and several pounds of selenium. To obtain these the gold is first precipitated from the solution by ferrous chloride, all the other metals by iron turnings. The precipitate is first submitted to the action of ferric chloride to dissolve the copper, and the residue is fused with charcoal and soda to separate the selenium. The regulus from this operation is dissolved, and a compound of selenium and palladium, or of these with platinum, is obtained. They are composed of equal atoms of the two metals and form hard brilliant plates. The presence of these metals in coins is less remarkable than in such ores as those of Commern and Mechernich on the west bank of the Rhine. These ores occur as small granules of galena in a soft sandstone, their origin being still a mooted point. The ore yields a very soft and pure lead, though the presence of pyrite prevents the manufacture of the virgin lead used in making the best brands of white paint.