The man in the oval frame here is Georg Honauer. On the left, we see his unusual execution. A Latinized inscription gives his pretended noble alias, Lord of Brunhoff and Grobeschütz, along with the year 1597 and his age: twenty-four years old. Honauer is richly dressed in an embroidered tunic and is wearing an extravagant plumed hat. Two little devils repose on cushions beneath him.

Spectators cluster round the elaborate gallows. The tall iron construction, complete with finial balls and dangling chains, stands on a specially cut stone plinth. In a gory detail, blood drips down from the hanging figure. There is reason both for the fancy dress and the fancy construction.

Honauer was born in Olomouc, Moravia (now in the Czech Republic), in 1572. Passing himself off under his alias as a goldsmith and alchemist, in 1596 he entered the service of Friedrich I, Duke of Württemberg, in Stuttgart, claiming to be able to convert iron into precious metal using a process that combined alchemical transmutation with the bulk techniques of metal ore smelting.

Most ancient cultures with metallurgy have a version of alchemy, from the Chinese to the Egyptians. Alchemy flourished in medieval Europe, with its promise of divinely assisted immortality and its alluring sub-discipline, chrysopoeia, the transmutation of base metal into gold. It came with its own compelling logic that metals in the earth exist naturally in a constant state of evolution toward gold. Ores were near the start of the journey; easily smelted base metals such as lead a little further along. Alchemists believed that with the right chemical agents they could accelerate the process. But others doubted these claims, and during the centuries when some were pursuing alchemy in all seriousness, others — from Chaucer and Dante to Pieter Bruegel the Elder and Ben Jonson — made it a topic of derision and satire.

Alchemists nevertheless found patrons among men in urgent need of money, and the duke was certainly one of these. Before the end of the decade, Friedrich would raise the cash to persuade Rudolf II, the Holy Roman Emperor and Archduke of Austria, to release his duchy from Austrian control, and was pursuing expensive utopian projects, such as building the new city of Freudenstadt as a Protestant refuge.

So Honauer’s arrival in Stuttgart was well timed. Friedrich was already offering a reward to subjects who discovered promising ore deposits. Honauer claimed he could produce eight hundred ducats’ worth of “fine gold” from a hundred pounds of iron, and a friend said he had seen him using a tincture to draw gold from a lead bullet at a military camp in Hungary. The duke demanded a small-scale demonstration, which Honauer duly performed, and the metallic product passed an assay by the duke’s mining adviser; it was “at least as good as ducat-quality gold”.

Driven by fascination with the subject of alchemy as well as his avarice, Friedrich immediately directed that his Stuttgart summerhouse be converted into a laboratory for Honauer, and granted him further facilities at Kirchheim unter Teck, a short ride away from the city. He placed a large initial order for 200,000 ducats of gold, but Honauer said he did not have a sufficient quantity of the reagents necessary for such a large undertaking. They agreed on a monthly target of 36,000 ducats, to run indefinitely. The duke then arranged for thirty-six hundredweight and eighteen pounds (nearly two tons) of iron to be transported more than 150 miles from his armoury in Mömpelgard (now Montbéliard in France) to provide Honauer with the “raw material” he needed. Honauer’s order for additional chemicals necessary for the operation was equally impressive: 1030 pounds of saltpetre, 1852 pounds of lead, as well as similar quantities of “white copper” (cupronickel) and “mountain antimony”, and other reagents.

However, when he finally saw the scale of the task before him, Honauer lost his nerve and fled the city. Keen to get him back, believing that he had seen transmutation with his own eyes, the duke had his court painter produce “wanted posters” for the vanished alchemist, who was soon apprehended and brought back to attempt the transmutation again. When this failed, Friedrich had Honauer interrogated. Although the duke clearly wanted to believe Honauer could do as he had claimed, the fact that the alchemist had run away could only add to suspicions he was a cheat — a Betrüger, to use a word adopted at this time specifically to categorize alchemists who had been found unsuccessful, and who might or might not have been deliberately fraudulent.

The trial that followed was complicated by the fact that Honauer was indicted for impersonating a member of the nobility as well as the alchemical Betrug. He was quickly found guilty and, despite a personal appeal to the Holy Roman Emperor, sentenced to hang in a unique public spectacle. On Friedrich’s orders, all the iron that Honauer had been unable to convert into precious metal was converted instead into his gallows. The thirty-foot structure was then gilded in mockery of his claimed abilities and, on April 2, 1597, Honauer was dressed in robes woven with gold brocade to humiliate him still further, and led out to his death.