Johan Rudolph Deiman

Johan Rudolph Deiman: The Amsterdam Doctor Who Split Water

In 1789, eleven years before the invention of the electric battery, two Amsterdam men pulled water apart using nothing but static electricity and put it back together by burning the pieces. Johan Rudolph Deiman and Adriaan Paets van Troostwijk sparked a fine tube of water with a friction machine, collected the gas, and showed that combustion returned it to water. It was the first electrolysis of water in history, performed by a practising physician and a merchant-amateur, working in a private laboratory in a country then sliding into political chaos.

An Orphan in East Friesland

Deiman was born on 29 August 1743 at Hage in East Friesland, the son of a solicitor named Albertus Deiman and his wife Volke Hiddes. His mother died when he was young; his father died around 1758, leaving him orphaned in his mid-teens. He was apprenticed to an apothecary at Leer — the trade that put a fatherless boy nearest to scientific work without requiring money.

The apothecary's shop was, in the eighteenth century, an unusually good chemical education. It meant handling reagents daily, running distillations and crystallisations, and learning to keep a preparation clean. Deiman went on from there to the University of Halle, studying medicine and philosophy under Adolph Böhmer and graduating in 1770 with a dissertation on vital indications. He then set up as a physician in Amsterdam.

The Circle

Medicine paid his bills. Chemistry was what he did with the rest of his life, and he did it in company. His long collaboration with Adriaan Paets van Troostwijk defined both their careers, and around them gathered a small group — including the botanist and chemist Nicolaas Bondt — that met to study chemistry as friends. In 1791 they formalised it as *De Bataafsche Societeit*, the Batavian Society, which grew in time into the Royal Netherlands Chemical Society. Deiman had been elected to the Hollandsche Maatschappij der Wetenschappen at Haarlem in 1783.

The group had a cause. Antoine Lavoisier's oxygen chemistry was in the process of destroying the phlogiston theory that had organised the subject for a century, and the Dutch circle became the principal channel through which the antiphlogistic system entered the Netherlands. Van Troostwijk himself had abandoned phlogiston around 1788. This was not a neutral scientific position in 1790; it was a partisan commitment to a French revolution in chemistry, taken by men in a republic about to be invaded by revolutionary France.

Water

The 1789 experiment is the work that endures. Water had been shown to be a compound of what we now call hydrogen and oxygen only a few years earlier, and the demonstration had run in one direction: burn the gases, get water. Deiman and van Troostwijk ran it backwards. Using electrical apparatus of the kind Martinus van Marum had brought to a high pitch at Haarlem, they decomposed water by electric spark and collected the resulting gas, then recombined it by combustion.

That two-way proof — take apart, put back together, account for everything — is what makes a chemical claim binding rather than suggestive. It is also, though nobody could see it in 1789, the ancestral form of every electrolyser now built for hydrogen production.

The pair continued. In 1790 they published on the electrical machine and the experiments they had run with it, sparking a range of gases and metal oxides. Sparking oxygen produced a sharp smell they noted without understanding — ozone, which would not be named or identified for another half-century.

Dutch Liquid

The circle's other durable product was a compound. Working with van Troostwijk and Bondt, Deiman prepared 1,2-dichloroethane from chlorine and olefiant gas — ethylene, itself obtained by the action of concentrated sulphuric acid on alcohol. The oily result was so closely identified with the group that chemists called it *Dutch oil* or *Dutch liquid*, and the name stuck for generations. Ethylene was for a long time known as *olefiant gas* precisely because it produced this oil. The compound was among the first organochlorines ever deliberately made, and the line from it runs directly into the industrial chemistry of the following century.

Why Johan Is Called a Genius

The quality on display in Deiman's best work is experimental rather than theoretical: the ability to see that an instrument built for one purpose — an electrostatic machine, essentially a physics demonstration device — could be turned on a chemical question and made to yield an answer nobody had extracted before. Crossing that boundary between disciplines, in an age when the disciplines were only just forming, took a particular kind of imagination. So did the discipline of the proof: decomposition and resynthesis in the same paper, so that the result could not be argued away.

The counter-case is substantial and worth stating without flinching. Deiman never worked alone. Every one of his significant results carries at least one other name, usually van Troostwijk's, and historians of chemistry have generally treated van Troostwijk as the senior partner. He proposed no theory of his own; he was an exceptionally capable executor and advocate of someone else's — Lavoisier's. And his signature achievement was superseded with brutal speed: within eleven years William Nicholson and Anthony Carlisle repeated the electrolysis of water with Volta's new pile, obtained the gases cleanly at separate electrodes, and effectively founded electrochemistry. Deiman's static-spark version became a footnote in the story of the thing it started.

What holds up is priority and rigour. He was first, and he was careful, and the experiment he ran in 1789 is the origin point of a technology now central to the world's energy plans. That is a real claim, and it does not need inflating.

Legacy

Near the end of his life Deiman was appointed physician to Louis Bonaparte, installed by his brother as King of Holland — an odd final honour for a man who had spent his career importing French chemistry into a Dutch republic that no longer existed. He died on 15 January 1808, a year into the appointment.

The society he helped found survives. So does the phrase *Dutch liquid*, still occasionally used for 1,2-dichloroethane. And every hydrogen electrolyser now being built descends, through a long chain of improvements, from the moment in 1789 when a physician in Amsterdam ran a spark through a tube of water and watched it come apart.