METALS are a very numerous class of simple bodies, and are distinguished by their very peculiar lustre arising out of their opacity and reflective power in regard to light. They conduct electricity and heat ; and they have not been re solved into other forms of matter, so that they are regarded as simple or elemen tary substances. When their compounds are electrolysed the metals appear at the negative surface, and are hence consider ed as electro-positive bodies. They are enumerated in the following table, to gether with the names of the chemists by whom they were discovered, the date of their discovery, their specific gravities, melting points, equivalent or atomic weights, and symbolic abbreviations. For their individual distinctive charac ers, see the respective metals.
The specific characters of minerals are three. Specific gravity, hardness, and crystaline form, which last is either rhombohedral, pyramidal, prismatic, or ttssular ; i. e., hexagonal. A collection of similar species are a genus, of general an order, and of orders a class.
There are seven metals with proven al kaline bases; potassium, sodium, barium, strontium, calcium, magnesium, and lithium.
There are six with earthy bases ; alu minum, glucinum, cerium, yttrium, zir conium, and thorium ; i. e., formed by reducing the earths to metals by ab stracting oxygen from the earths. When these metals are oxidized, the products are white powders, without flavor. The rest of the metals can hardly be classed together, as they have few properties in common.
Oxides of iron, nickel, cobalt, and man ganese, are irreducible in fire, but dis solve in acids.
Oxides of gold, platinum, and four others, are reduced to the metallic state by heat 'alone, and they require great heat to oxidate them.
Metals, in general, seek to return to their original state as oxides, with two or three exceptions of the harder kinds, arising apparently from the excess of a silicious or quartz base over the alkali, combined during their electrical genera tion.
Despretz Fives the following table of the conducting heat of metals according to the following figures :— Gold, 1000 ; platmum, 981 ; silver, 973; copper, 898; iron, 374; zinc, 363; tin, 304; lead, 179.6.
Becquerel gives the electrical conduct ing power as follows : Copper, 100; gold, 93.6 ; silver, 73.6 ; zinc, 28.3; platina, 16.4; iron, 15.8; tin, 15.5; lead, 8.3; mercury, 3.5; potassium, 1-33.
The most ductile and malleable of the metals, in order, are cadmium, copper, gold, iridium, iron, lead, &c.; and tin and zinc the least.
The most brittle, are, antimony, ar senie, bismuth ; and tungsten, titanium, and uranium the least.
The most facile for wire poles, in order, are gold, silver, platinum, iron, copper, zinc, tin, lead, and nickel.
The easiest made into plates, or sheets, by rollers, in order, are gold, silver, copper, tin, platinum, zinc, iron, and nickel.
When metals require to be granulated for manufacturing purposes, they are poured into water, or briskly agitated in a box while congealing, by which they i fall into powder instead of crystalizing. A cnllender, or ladle with holes, is used in dropping into water.
Silver may be reduced to fine grains by first dissolving it in nitric acid, and then immersing a plate of copper, to which the silver will attach itself; but it must be shaken off till the greater part of the silver has settled at the bottom, when the copper and solution may be taken away, and the precipitate washed and dried.
Copper may be obtained in grains in like manner, by immersing a plate of iron In a solution of the copper and sub phonic acid. When the iron plate is put in, a little more sulphuric acid should be added, and the copper will fall to the bottom, after which it should be washed with dilute sulphuric acid, and with water, and dried.
To obtain gold in powder, dissolve it in muriatic acid, and then add protosul phate of iron. - The gold will be precipi tated, and then it should be washed with some muriatic acid, and with water, and dried.