Platinum was first found in South America, and was then named from its appearance, platina being the Spanish diminutive of plata (silver). But it has been called polyxene because it is so hospitable to otker minerals that it is rarely found alone. Almost invari¬ably it has some traces of the similar metal in the Mendeleef group and table—osmium, iridium, ruthen¬ium, rhodium, palladium. Very often, too, it is found in gold deposits, and with copper or iron. Sometimes it is found as cubic crystals; sometimes as flattish scaly grains; sometimes as nuggets.

Most frequently, however, it is found in sandy deposits; and in the Middle Urals, where the most famous deposits are situated, nuggets up to 20 lbs. in weight have been discovered. It was said that the Bolsheviks paid for their propa¬ganda in Denmark by large consignments of platinum, the amount sent to Copenhagen being., valued at £20,000. As about 95 per cent, of the available plati¬num comes from Russia, the Government controlling that part of the country from which come such stocks has a very valuable source of wealth.

Platinum is a strange, silvery-looking metal which expands when heated at almost the same rate as glass. Platinum wire can, therefore, be melted into glass without the danger of the glass cracking when both cool, hence its use in the glass bulbs of electric lamps.

It is heavy, can be beaten out or drawn out readily ; but it is almost unacted upon by air or acids. It has the strange property of absorbing considerable quantities of gases like hydrogen; and, besides its use for incandescent bulbs, it is turned into jewellery, and is used in photography and for the manufacture of chemical apparatus. One of its uses belongs to an obscure chemical operation known as catalysis. Sir Humphry Davy, just a century ago, exhibited what he called a “lamp without flame.” He suspended a spiral of platinum in ether whose vapours joined on the platinum with the oxygen of the air causing the metal to glow. The point of this and similar experiments is that the ether might be left in contact with the iron for ages without any change taking place. We mav keep a mixture of oxygen with double the amount of hydrogen in a closed vessel almost as long as we like without any action taking place.

We know that these are the ingredients of water, and that if we brought a flame near or introduced an electric spark there would be a flash and an almost instantaneous chemical change. But we can produce the same result if we introduce a clean strip of platinum foil. The combination takes place. Water is produced; and sometimes the platinum begins to glow and the last of the gases explode. If the platinum be examined afterwards it is no lighter in weight and no change can be found in it. If it be kept quite clean and not fingered it can be used for the same mysterious operation again.

There are a number of other instances of catalysis in which platinum has been used. Some of them have not as yet been applied industrially, though students have seen the method employed in the laboratory. Such an experiment is the passing of air or oxygen into a flask containing a solution of ammonia and a spiral of platinum wire. At first the flask is filled with dense white fumes of ammonia compounds ; but later, when the oxygen is passed in quickly, orange fumes of nitro¬gen peroxide appear, and the explosive gases at length take fire from- the glowing platinum. The nitrogen peroxide being of the greatest value for the production of nitric acid some use has been made of the process in Germany.

Magnetite, or magnetic iron ore, which contains over 60 per cent, of iron, is found principally in Sweden and the Lake Superior district in the New World. The iron from the Swedish mines of Dannemora is said to be the purest in the world, yielding at least 66 per cent, of metal. The owners limit the output to about 50,000 tons per annum, and keep a special price. Read the rest of this entry »

Iron, of all the important metals, was the last to be employed generally and extensively, although when so used it quickly eclipsed in importance all the other metals.

Yet iron is to be found in almost every country in the world, and so much is there in India that it must have been known in that country in early times. Read the rest of this entry »

In more modern times the Malay Straits and the tin-fields of Nigeria have attracted the tin-seeker else¬where, but the Cornish miner is still sought even in these remote quarters of the globe. Read the rest of this entry »

Tinstone or cassiterite is now found in Cornwall, Malay Straits, Peru, Bolivia, Queensland, New South Wales and Nigeria, but the oldest of these tin-bearing areas is Cornwall, the mines of which, in spite of the efforts of the Phoenicians to keep them secret, soon , became famous to the ancient world. Diodorus Siculus, a century before Christ, relates that the inhabitants of Britain ” prepare tin, working the earth which yields it with great skill. The ground is rocky but has earthy veins, the contents of which are brought down, melted and purified. After casting this into the form of cubes they carry it to a certain island adjoining Britain, called Iktis. During the ebb of the tide the space intervening is left dry and they transport there quantities of tin in carts. From hence the merchants buv tin from the natives and carry it into Gaul, and through Gaul on foot for thirty days to the mouth of Rhone.”

At a later date Cornish tin became one of Britain’s principal exports, and English monarchs dabbled in tin speculations, not always successfully. In this connec¬tion Sir Isaac Newton tells an interesting story of Queen Anne:

” The 1600 tunns of tin bought annually in Cornwall amounts, in merchant’s weight, to 1714 tunns yearly, and in all seven years to be 12,000 tunns. Between April 6, 1704, and September 12, 1705, there has been sold by the Pewterers 600 tons, by the officers of the Mint 488 tons, and by Mr Drummond about 1000 blocks, or 144 tons—in all 1232 tons. The Queen pays annually for tin, £112,000, salaries £3000, carriage by sea £3000, incidental charges about £1200—in all £118,200 ; and in all the seven years £827,000, besides interest. Her Majesty has received . . . £65,360 annually, and in all the five and a quarter years to come £343,140. Deduct the £65,860 from the £118,200, and the £343,140 from the £827,400, and the Queen will run in debt yearly £52,840, and at the end of the time of the bargain will be in debt £484,260, besides interest, which amounts to about £72,000 more; so that the whole debt will be about £556,000.”

Copper, like silver, has been the victim of a ” corner,” and in 1889 the enormous dealings in copper culmin¬ated in a disastrous debacle, spreading ruin far and “wide,” even to the suspension of banks. Not the least romantic episode in copper as a commercial commodity is the story of the vicissitudes of the Rio Tinto Copper Mine, said to be the largest in the world. This mine, covering eight square miles in extent, was worked by many wealthy people, including the Spanish Govern¬ment, without success, but since its absorption by a large English company it has become one of the best-paying of mining concerns, and produces about one-tenth of the copper in the world. Read the rest of this entry »

In modern times the uses of copper in war material are innumerable, and there is practically no alterna¬tive mineral. Take, for example, the cartridge cases. Those for rifles, with alloy of copper and zinc, are so thin that the metals must be very pure to ensure against flaws. Those for quick-firing guns must be exact to a five-hundredth part of an inch and gas-tight. On shells copper bands encircle the steel. Copper wire is also necessary for field telephones and dynamos. No wonder that during the Great European War Germany was paying £160 or more in gold for every ton of copper in any form delivered over the German frontier, although in Britain its value was only £60. Read the rest of this entry »

Copper itself, however, as an implement of warfare still maintains a conspicuous place as a metal of commerce.
Copper is a brilliant metal of a peculiar red colour. The only other metal anything like it in colour is titanium.
Like other minerals, copper is not only found in large quantities in mines, but its presence has been discovered in all kinds of soils and waters. You can trace it  in seaweed, cheese, meat, eggs, straw and even in man’s liver, kidneys and blood.

The earliest mining of copper appears to have been done by the Egyptians in the Sinai Peninsula, where the tunnels, crucibles and parts of the tools used may , still be seen. They were worked from 5000 B.C. to 1200 3.c. In Europe also they must have been worked at a very early date, as in Spanish copper lodes there have been discovered flint mining implements and skulls of a prehistoric type.
Copper was known and worked by the Greeks and Romans and, alloyed with tin, it became the first metallic compound used by man, under the name of “bronze.” The Romans worked copper in Britain and Spain; and in the latter country the copper mines of the Rio Tinto are still very valuable.

In the New World the copper districts of Lake Superior indicate that primitive man worked there, using stone hammers and hide bags to remove the metal hacked off in lumps. The Aztecs and natives of Peru also used bronze implements in their gold, silver, tin and copper mining, so they had discovered the usefulness of the alloy.

Bronze, the remaining metal used for coins as a medium of exchange, is not a pure metal, but a mixture of copper and tin. Many of the early nations used copper coins, and copper pennies were in use in England between about 1760 and 1860, when bronze was sub¬stituted. Bronze weapons also succeeded those of the Stone Age, only to be superseded later by the more formidable iron.