In ancient times, there were often ships carrying gold, silver and jewels in the Caribbean. One day, an ocean-going fleet discovered "inferior silver"-a silvery white silver. In order to get more benefits, profiteers quietly brought these "inferior silver" back to their homeland and sold them to jewelers at low prices. In order to make more money, some jewelers ask craftsmen to mix "inferior silver" into gold, and some even simply copy it into gold coins for circulation in the market. This has seriously affected the local economic order.

After the local officials reported this to the king, the king was furious and ordered all the "inferior silver" to be poured into the sea, and anyone who hid it should be asked to cut it. After receiving instructions, officials dumped a large amount of "inferior silver" collected into the turbulent sea. Since then, this inferior silver has never passed through the market again.

So, what is this inferior silver? Why can we confuse true and false? It turns out that this is platinum, which is chemically inactive, stable in air and humid environment, and not corroded by ordinary acids, alkalis, salts and organic substances at room temperature; Moreover, platinum is dissolved in aqua regia and melt; It can react with sulfur, phosphorus and halogen at high temperature. In addition, platinum, palladium and rhodium can be used as electroplating layers, which are mainly used in electronic industry and jewelry processing.

Platinum is a silvery shiny metal with chemical symbol Pt, atomic number 78 and atomic weight 195.08. It belongs to the eighth group of the periodic table and is a member of platinum group elements. Platinum has a melting point of 1772℃, a boiling point of 3827.00℃ and a density of 21.45g/cm3 (20℃). Platinum has the characteristics of soft metal and good ductility, thermal conductivity and electrical conductivity.

Another form of platinum is platinum sponge, which is a gray spongy substance. This platinum sponge has a large specific surface area and strong absorption capacity for gases (especially hydrogen, oxygen and carbon monoxide). Powdered platinum black can absorb a lot of hydrogen. When platinum is heated below 450℃, a platinum dioxide film is formed on the surface, which can react with sulfur, phosphorus and halogen at high temperature. Platinum is insoluble in hydrochloric acid, sulfuric acid, nitric acid and alkali solution, but soluble in aqua regia and molten alkali. The oxidation states of platinum are +2, +3, +4, +5 and +6. The compounds easily formed by platinum are [Pt (NH3) 2] Cl2 and K [Pt (NH3) Cl5]. Other metals related to platinum are ruthenium, rhodium, palladium, osmium, iridium and gold. They exist almost completely as elements in nature, and their content in the earth's crust is similar to that of gold, and their chemical inertness is equivalent to that of gold, but their discovery and utilization are far behind that of gold. Their extreme dispersion in nature and their high melting point may be the reasons for this situation. The largest natural platinum block found so far is 9.6 kg. We know that the melting point of platinum is 1772℃, that of ruthenium is 23 10℃, that of rhodium is 1966℃, that of palladium is 1552℃, that of osmium is 2054℃ and that of iridium is 24/. So although they belong to the same system, they have different melting points.

In South America, ancient Indians have used platinum and gold to synthesize decorations. Because the content of platinum in platinum series minerals is much higher than other elements, it was first discovered among platinum series elements. The first mention of platinum in Europe may be in the book published by French mineralogist Scari Ji 1557. He said that all metals can be melted, but there is one kind of metal that can't be melted in Darian Mine and Darinan (now Panama). Here, the unmelted metal may refer to platinum.