Lothar Meyer

Lothar Meyer: The Other Man Who Found the Periodic Law

In 1869 Dmitri Mendeleev published his periodic table. Months later, Lothar Meyer published his own — arrived at independently, grounded in physical measurement, and comprehensively too late. Meyer acknowledged the Russian's priority without complaint, and in 1882 the Royal Society split the Davy Medal between them. History has been less even-handed than the Royal Society, but the periodic law had two discoverers, and one of them was a German physician who came to chemistry by way of blood.

A Physician's Son

Meyer was born on 19 August 1830 in Varel, in the Duchy of Oldenburg, the son of the physician Friedrich August Meyer and Anna Biermann. He was educated at the Altes Gymnasium in Oldenburg and then went, as expected of a doctor's son, into medicine.

His training reads like a tour of nineteenth-century German science at its peak. At the University of Zurich from 1851 he studied medicine under Carl Ludwig, the great physiologist. At Würzburg from 1853 he studied pathology under Rudolf Virchow, the founder of cellular pathology. At Heidelberg he worked under Robert Bunsen, who held the chair of chemistry — and it was Bunsen who redirected him. In 1858 Meyer took a doctorate in chemistry at the University of Breslau with a thesis on the effects of carbon monoxide on blood. Not content, he then went to Königsberg to study mathematical physics under Franz Ernst Neumann, with Gustav Kirchhoff among his influences.

The combination is the key to everything he later did. Meyer was a physician who had been trained in physiology, pathology, chemistry and mathematical physics, and he approached the elements as a physicist would: looking for quantities that could be measured and plotted.

Oxygen and Haemoglobin

The medical training paid off immediately. Meyer recognised that oxygen combines with the haemoglobin in blood — an insight that turned respiration from a vague vital process into a specific chemical union between a gas and a substance in the blood. It remains one of the foundation stones of physiological chemistry, and it was the work of a man not yet thirty.

The 1864 Book

In 1859, after habilitating, Meyer became a Privatdozent in physics and chemistry at Breslau. Five years later he published *Die modernen Theorien der Chemie*, the book that made his reputation and that contained an early version of the periodic table: twenty-eight elements arranged into six families according to valence.

The significance is easy to miss from a distance. Chemistry in 1864 possessed a long list of elements and no accepted principle for organising them. Meyer's table was a genuine first attempt to sort the elements systematically by a property that mattered, and to argue that the sorting revealed something real about matter.

Atomic Volumes

His most original contribution was graphical. Meyer plotted a line chart of atomic volume as a function of atomic weight, and the resulting curve rose and fell in a series of peaks and troughs. Here, drawn on a single sheet, was the periodicity of the elements — not asserted, not inferred from chemical analogy, but visible. It converted the periodic law from a classification scheme into a physical fact demanding explanation, and no one who saw the curve could easily dismiss the pattern as coincidence.

Meyer went on revising. The 1864 table was laid out horizontally; a further version in 1870 was arranged vertically, with each series properly terminated by an element of the alkaline earth metal group.

Beaten by Months

By the time that fuller version appeared, Mendeleev had published. The two men had worked entirely independently and reached substantially the same law, and Meyer said so, acknowledging Mendeleev's priority.

There was, however, a real difference between them, and it explains the divergence in their fame. Mendeleev pressed his table into the business of prophecy, emphasising the elements not yet discovered and describing the properties they would be found to have. Meyer did not. He did not stress predictions of unknown elements or detail their likely characteristics; he had established the pattern and was content to let it stand as a pattern. Prediction is what makes a scientific law famous, and Mendeleev's name is on the law for that reason.

The Royal Society, at least, judged the work rather than the showmanship. In 1882 it awarded the Davy Medal jointly to Meyer and Mendeleev in recognition of their work on the periodic law.

Benzene, and the Chairs

Meyer's career moved steadily upward: a post at the Eberswalde Forestry Academy in 1866, a professorship at the Karlsruhe Polytechnic in 1868, and in 1876 the chair of chemistry at the University of Tübingen, which he held for the rest of his life. He married Johanna Volkmann in 1866.

He also made a second structural contribution that is often overlooked. In 1872 Meyer was the first to suggest that the six carbon atoms of the benzene ring are joined to one another by single bonds only, with the fourth valence of each carbon atom directed inward, toward the interior of the ring. It was a proposal that moved the ring's remaining bonding capacity away from fixed links between particular atoms and into the structure as a whole — a way of thinking about aromatic molecules that outlived the specific model.

Tübingen, 1895

Lothar Meyer died in Tübingen on 11 April 1895, following a stroke, at the age of sixty-four. In 1983 a newly identified mineral was named lotharmeyerite in recognition of his work on the periodic law — a modest memorial for a man who saw the same great pattern as Mendeleev, drew it more beautifully, and said it out loud a few months too late.