42 
the other heavy metals. Scientifically they have been 
divided according to their physico-chemical properties into 
electro-positive and electro-negative bodies. Among the 
electro-negative class, tellurium, arsenic, and antimony, 
are found nearest to the series of metalloids, inasmuch 
as they mineralise other metals, like sulphur, selenium, 
etc. ; those principally forming acids are, chromium, 
molybdenum, vanadium, tungsten, tantalum, pelopium, 
niobium, titanium, and osmium; to the positive class 
belong, in addition to the precious metals, mercury, copper, 
uranium, bismuth, lead, cerium, lanthanum, cobalt, nickel, 
iron, cadmium, and zinc; the last is the most positively 
electric, and thus is associated with the light metals of the 
earths (yttrium, zirconium, aluminum, glucinum, and mag¬ 
nesium), and also to those of the alkalis (calcium, strontium, 
barium, lithium, sodium, and potassium), of which the last 
is the most positive of all. As the metals just mentioned 
are not all of equal importance, in what follows we limit 
ourselves to the most important of these, and refer the 
reader to the larger hand-books and treatises on mineralogy 
and chemistry. 
The metals have from the earliest times attracted the 
eyes of man by their lustre, hardness, ductibility, mallea¬ 
bility, fusibility, and durability, and this was especially the 
case with those which occur native, especially gold, silver, 
and copper, while platinum (and the other platinum metals) 
was first found, since the discovery of South America, by 
Ulloa in the year 1735, and recognised as a proper pre¬ 
cious metal by Scheffer in 1752. Iron has also been long 
known not only to the Israelites and Asiatic nations, as is 
clearly proved by a passage in the Old Testament, but it 
appears that the metallic lustre of the magnetic iron-stone, 
of such frequent occurrence in the East and in the interior 
of Africa, and perhaps also of the specular iron, had early 
induced the inhabitants to endeavour to melt it by means 
of wood or coal, and so to produce a more or less malle¬ 
able rod-iron. Mercury and tin also, as well as the bronze¬ 
like copper alloys, have been long known to man, as the 
writings of the ancients testify. It also appears that these 
metals were principally introduced into commerce by the 
Phoenicians. The influence now exerted by the metals in 
the arts and sciences, and on commerce, is generally known ; 
and in order to give a slight notion of the great importance 
of the metals, we need only allude to the various appli¬ 
cations of iron to instruments and machinery of all kinds, 
to the employment of silver and gold in coining and in 
traffic by exchange, as well as for ornament of every variety ; 
moreover, to the applications of platinum to chemical and 
physical apparatus, of mercury and antimony in medicine, 
of cobalt, chrome, uranium, and lead, to the manufacture of 
colours, for enamel, and other purposes; of antimony, lead, 
and tin in the manufacture of printing-types, of copper to 
electro-plating, and of steel and copper to the production 
of steel and copper plates for engraving. 
In the crust of the earth the heavy metals play 
a subordinate part in comparison with the light metals 
of the earths and alkalis, especially with alum, calcium, 
and sodium; and iron alone, the most useful and at 
the sametime the most harmless, is generally diffused, it 
is for the most part accompanied by a small quantity of 
manganese, while the others only appear subordinatelv, 
mineralised in veins and beds, sometimes disseminated, 
and are obtained with great labour from a considerable 
depth. Gold and platinum seem to be exceptions, in 
so far as they are also found, the former often in large 
quantites, in wet land ; and in a few places, as, for instance, 
in North America, copper appears on the surface, and silver 
in Peru. The native iron, which occurs here and there 
on the surface of the earth, is generally meteoric iron, and 
does not come into the same category. 
I. NOBLE OB PBECIOUS METALS. 
PLATE XIII. 
Fig. 1—7.—Gold, Native Gold. 
One of the longest known metals, which has been 
always highly valued on account of its fine colour, mallea¬ 
bility, capability of polish, and ductility. It is the only 
yellow metal which occurs native, and by its malleability 
is easily distinguished from the few yellow ores which 
occur, namely, copper, iron, and nickel pyrites. It occurs 
almost always native ; it is, however, always mixed with 
more or less silver, which takes away from its specific gra¬ 
vity as well as from its colour, the deep-yellow becoming 
lighter. Native silver also always contains a small amount 
of gold. 
Native gold occurs crystallized, in cubes, octahedrons 
(Fig. 2), combinations of the cube with octahedron and 
dodecahedron (Fig. 3), or in crystalline foliated masses 
(Fig. 4), most frequently in compact roundish grains, im¬ 
bedded in, or aggregated on a finely granular reddish quartz, 
as, for instance, in California (Fig. 1) and Australia (Fig. 9). 
Still more frequently it is found in alluvial deposits in the 
form of a finely foliated powder as gold dust, like Fig. 8, 
or in variously-shaped flat grains, which, by rubbing on 
the sand, often have a polished appearance, like Fig. 7 ; 
both of these occur in California; or also in long, flat 
lumps, with a rough upper surface, like Fig. 6, which is 
from the alluvium of the Gold Coast. The larger lumps, or 
nuggets , of rounded forms, are exceptions, as represented 
on a reduced scale in Fig. 5. This remarkable specimen 
was found in Victoria in the year 1852, and weighed 27 
pounds 6 ounces. It was 11 inches long and 5 thick, 
and it had the appearance of an oblong melted mass. A 
still larger lump was found in California in 1855; it 
weighed 160^- pounds, and was mixed with quartz, which 
weighed about 15 pounds. It was sold for 40,000 dollars. 
In the alluvium of the Urals pieces of 27 and 87 pounds 
have been found, and very considerable masses at Concep¬ 
tion in Chili. That gold was in earlier times also found in 
much greater quatity in Asia and Africa is testified, among 
other things, by the description in holy writ of the building 
of Solomon’s temple, and of the immense masses which were 
