METALS- METALLURGY. 



OF the sixty-four elementary substances at 

 present known, about fifty are metals, but 

 the greater number of these are rarely seen, and 

 still more rarely applied to any useful purpose in 

 the metallic state ; although some of those incap- 

 able of being so used form highly important com- 

 pounds with non-metallic bodies, as will be found 

 explained in our numbers on CHEMISTRY and 

 USEFUL MINERALS. We shall devote this num- 

 ber almost entirely to those metals whose proper- 

 ties, such as strength, hardness, elasticity, malle- 

 ability, ductility, fusibility, and durability, render 

 them of great and indispensable service to man, 

 and refer but briefly to such as are of little or no 

 economic importance. The term metal is less 

 easily defined now than formerly, when certain 

 physical characters, such as lustre and high 

 density, were alone taken into account; because 

 we have come to know that a high metallic lustre, 

 for example, is possessed by a few non-metallic 

 substances, and that some metals are extremely 

 light bodies. Still, the properties above enumer- 

 ated, together with a high conducting power for 

 heat and electricity, suffice to distinguish the 

 metals as a class from other elementary sub- 

 stances. 



Mercury is the only metal which is liquid at 

 ordinary temperatures, although, with one excep- 

 tion, they can all be melted by the action of heat. 

 Most of them are non-volatile, except at very high 

 temperatures, produced by exceptional means ; 

 but a few, like zinc and cadmium, go off in vapour, 

 at a bright red-heat ; while arsenic, when heated 

 to a dull redness, passes at once from the solid to 

 the gaseous state. Some metals and alloys, as 

 chromium and a combination of iridium and 

 osmium, are excessively hard, much more so than 

 the hardest steel. Some, again, like lead and gold, 

 are soft ; but far softer, and yielding to the fingers 

 like putty, are such metals as potassium and 

 sodium. It is necessary, however, to keep in 

 mind that the degree of softness in ordinary com- 

 mercial qualities of a metal will vary much with 

 even slight amounts of impurities. 



METALLIC VEINS AND BEDS. 



A few metals are found in the metallic state, in 

 which case the term native is applied to them. 

 Gold and platinum are always, while silver and 

 copper are frequently so found ; but others, again, 

 like iron and lead, except in rare instances, only 

 occur in nature in union with other substances, 

 forming minerals called ores. The great majority 

 of metals are obtained from their ores, which are 

 most frequently oxides, carbonates, and sulphides ; 

 but chlorides, arsenides, phosphates, and other 

 compounds likewise occur. As their names 

 imply, these are chemical combinations of the 

 metals with other elements, although most ores 

 are also mechanically mixed with sparry or earthy 

 impurities. Many ores, again, contain more than 

 one metal ; thus, silver and lead, iron and copper, 

 26 



cobalt and nickel, are very frequently found 

 together. 



Most metallic ores are found in veins, techni- 

 cally called lodes j but certain kinds of iron ore, 

 and more rarely copper ore, are found in beds 

 or strata. Gold nuggets are largely found in 

 stratified drifts, which, however, have been re- 

 moved from their original position in veins by 

 denudation. Veins are rents, fissures, or hollow 

 spaces in stratified or unstratified rocks, filled 

 with spars such as quartz, calcite, barytes, and 

 fluor, when non-metalliferous ; and when metal- 

 liferous, with some ore along with these spars. 

 Metalliferous veins which run nearly east and 

 west are called right-running veins, and these 

 are usually the richest, longest, and most con- 

 stant in character. Other veins crossing these 

 at right angles, or nearly so, are termed cross 

 veins, these being not only shorter, but more 

 variable in width than the former. A third inter- 

 mediate class of veins, and short, irregular 

 branches, takes all directions. In the mining 

 districts of Great Britain, veins or lodes vary 

 from a fraction of I foot to about 40 feet thick, 

 their average thickness being 3 or 4 feet. The 

 length of some is from 7 to 10 miles, but with 

 such as these there is usually a doubt whether it 

 is really the same vein throughout its length. 



METALLURGY. 



This word is from the Greek metallon, ore, 

 metal, and ergon, work. A distinguished living 

 metallurgist states that, as now understood, the 

 term signifies the art of extracting metals from 

 their ores, and adapting them to various purposes 

 of manufacture. As we cannot describe a single 

 smelting process, or system of processes, which 

 will hold good for several metals, it will be neces- 

 sary to treat the smelting of each by itself. But 

 previous to doing this, we give a table (on next 

 page) of nearly all the known metals, with their 

 melting-points and specific gravities, as far as 

 they have been ascertained. There are a few 

 metals besides those mentioned namely, thori- 

 num, tantalum, caesium, indium, and one or two 

 more about which very little is known. 



Gold 



Since the eye of primitive man first lighted upon 

 gold, no other metal, perhaps no other substance 

 even, has surpassed it in interest. Its name is 

 derived from the word our or or, which signifies 

 in many ancient languages the light of day. 

 Although iron is a far more indispensable material 

 to mankind, yet there is a peculiar charm about 

 the colour, the indestructibility, the intrinsic value, 

 and other properties of gold, by which its place 

 as the most highly prized of the metals will 

 always be maintained. Even in early ages it was 

 found in many localities, and is now known to 

 be very widely distributed, although there are 



