The earliest references to the use of platinum are to be found in Egypt at the time of the Old Kingdom. Specks of platinum group metals occur in ancient Egyptian gold work as a ‘contamination’. Because of platinum’s high density, chemical inertness and hardness, it remained with the gold throughout all purification attempts and was subsequently incorporated during the metalworking process. But these are just little specks, more substantial are the hieroglyph decorations on a copper alloy box from the 7th century BC which was excavated at Thebes. The box can be dated quite accurately because it carries the name of Shepenupet II who was an Ancient Egyptian princess of the Twenty-fifth dynasty (around 700 BC to 650 BC). A famous chemist named Marcellin Berthelot (1827-1907) reported in his 1901 work ‘Comptus Rendus'¹ that he found the hieroglyphs on the back of the box to be composed of a platinum and gold alloy. Whether this was a deliberate use of platinum or a coincidence,( the maker could have mistaken a platinum-gold nugget for an electrum one) isn’t clear. Given that this appears the only use of a platinum alloy by Egyptian goldsmiths, however, it is likely that the latter is the case.

How different it was on the other side of the Atlantic, some 500 years later. Indians of the La Tolita culture, living on the border between Colombia and Ecuador near platinum-rich alluvial deposits, started to use platinum alloys in their jewelry. Quite a few artifacts such as nose rings, masks and earrings have been found to contain platinum parts, deliberately separated from other metals and crafted to form white metal objects. Quite an achievement, considering that the melting point of platinum lies at 3221.6 °F (1772.0 °C)! How did they do it?

The alluvial deposits which formed the source for platinum in the La Tolita culture mainly contain traces of the metal in the form of minute grains, although the odd bigger nugget is known to have been found. These rare, larger nuggets could theoretically be worked straight out of the river when they were of a suitable, malleable alloy. Only one such a piece is known, David Scott & Warwick Bray of the London University report:

Although native copper-iron-platinum alloys occur in Colombia they are uncommon; there is one known example from the area of a copper-platinum alloy nugget being used to make a small penannular nose-ring.²

So… that explains the origin of one object. What about the others? The Indians must have had more advanced methods to craft their platinum alloy objects. Paul Bergsoe, a Danish engineer, conducted detailed experiments on Indian platinum objects in the 1930s and shared the following:

The small grains of platinum were mixed with a little gold dust and small portions placed upon a piece of wood-charcoal. When the gold runs it will coat the grains of platinum with gold. The grains are simply “soldered” together. If the piece is now further heated by means of the blow-pipe, let us say, the following will take place: a portion of the fused gold permeates the platinum and simultaneously a little of the latter is dissolved in the molten gold. This mixture of gold and platinum can now withstand a light blow of the hammer, especially when hot. By alternately forging and heating it is possible gradually to build up an homogeneous mixture. All the specimens found are small, which is natural, since they cannot be larger if they are to be exposed to the maximum degree of heat that can be produced from a bit of charcoal and a blowpipe.³

Apart from using this technique to create a platinum alloy suitable to craft small solid objects, the goldsmiths of the La Tolita culture also used the sintered platinum alloy to create foils. The acquired thin sheets of platinum were then used to plate gold objects by hammering and heating them onto the pre-formed gold.⁴

European Experiments

By the end of the 17th century, the Spanish had discovered the gold deposits of present-day west Columbia and in doing so ran into the native platinum. Completely oblivious to the advances achieved by the Indians in the field of platinum alloy production, the Spanish conquistadors labeled the metal ‘little silver’ and dismissed it as a valuable metal because it wouldn’t melt with any of their known methods. Records of mines closing due to the presence of ‘platina di Pinto’ show that platinum was a nuisance to the Spanish gold miners who considered it a contamination they couldn’t get rid of.

In 1741, an Englishman named Charles Wood laid his hands on some Columbian native platinum. He passed the samples on to his brother-in-law, William Brownrigg who was a physician and scientist in England. Brownrigg conducted some experiments and finally introduced the metal to the members of the Royal Society in 1750 where it was recognized as the ‘8th metal’ (next to the traditionally known metals: Gold, Silver, Copper, Iron, Tin, Lead and Mercury).

The history of platinum continues in France, where in 1758 a Professor in Chemistry, Pierre-Joseph Macquer, had a huge burning mirror built in order to attempt the melting of platinum, an event which proved to be successful but laborious. Several attempts, with small buttons of malleable platinum as an outcome, took place over the next twenty years, almost all in or around Paris by various scientists. None of these men was able to produce workable platinum in any significant quantities though.

That honor befalls Pierre Francois Chabaneau (1754-1842), a Frenchman who, from 1781 on, was working in Spain as a French and Physics teacher at a seminary near San Sebastian. Shortly after 1783 he took the chair of Chemistry and made the production of malleable platinum his mainstay. In 1786, after just three years, he had developed a very successful method. The King of Spain ordered the secrecy of the process and gave Chabaneau a laboratory devoted to the refinery of platinum. The output of Chabaneau’s laboratory became so large that the period from 1786 until the French Invasion in 1808 is called the ‘Platinum Age in Spain’.

The process by which Chabaneau created malleable platinum is said to be a powder metallurgic one. Powdered platinum, acquired from grinding the brittle substance that was the product of early platinum purification, would be pressed, heated and hammered in order to obtain a solid, workable ingot.

Around that same time a French court jeweler, Marc Etienne Janety, was also working with platinum. In 1786 he crafted a sugar bowl out of platinum for Louis XVI. Janety used a different method than Chabaneau: the arsenic process. Platinum alloys with arsenic at low temperatures. From the molten platinum-arsenic mix a brittle, solid bar could be cast. Further heating in stages could then be applied to drive off the arsenic, producing a pure platinum bar that could be forged to shape. This method is extremely unhealthy and it’s a miracle Janety lived as long as he did.

The French Revolution (1789-1799), followed by the Napoleonic wars (1803-1815) completely disrupted scientific advances in France and Spain. As a result, the next chapter in the history of platinum takes place in England.

English Advances

Around the year 1800 two British scientists, William Hyde Wollaston and Smithson Tennant, acquainted since their days together at Cambridge University, joined forces in a quest to produce a commercially viable platinum alloy. Their research led to the discovery of the platinum group of metals. Wollaston discovered Palladium in 1802 and Rhodium in 1804. Tennant managed to identify two new members which he called Osmium and Iridium in 1803.

Wollaston produced large amounts of platinum, mainly serving the crucible and gun-producing markets. Due to its high melting point, platinum was (and still is in the case of crucibles) used to line the inside of crucibles and the touch holes of guns. The process used by Wollaston was kept secret until 1828 when he was persuaded to share his experiences with the members of the Royal Society.

His lecture revealed the following ‘recipe’:

1. Precautions were taken to remove iridium as completely as possible.
2. The platinum salt was decomposed at as low a temperature as possible “to occasion the particles of platina to cohere as little as possible; for on this depends the ultimate ductility of the product” and the grey product was rubbed between the hands to powder “so fine as to pass through a fine lawn sieve”.
3. Great care was taken not to use anything harder than wood to break up any aggregates and not to burnish the particles, since “every degree of burnishing will prevent the particles from cohering in the further stages of the process”.
4. The fine powder was washed well, removing any soluble salts, leaving a uniform pulp ready for pressing.
5. The slurry was introduced under water into the die, a well-greased brass barrel about 6 inches long, tapered slightly, and closed with steel plugs.
6. Pressure was applied to the plugs by a toggle press “in which the applied power was multiplied three hundred times or more”, to yield a hard cake.
7. The cake was heated to redness in a charcoal fire and then placed on a layer of clean quartz, covered by a refractory pot, and sintered for twenty minutes at the maximum temperature that could be reached in a wind furnace. It was then ready for careful hot forging.⁵

Step one of the recipe, the complete removal of iridium, makes very little sense, after all, we know now that iridium-platinum alloys are perfectly malleable and Wollaston must have known this considering his close relation with Tennant, the discoverer of this element. Why he chose to include this piece of non-information is unclear.