Fritz Haber

Fritz Haber: Bread from the Air, Death from a Cloud

A third of the world's annual food production depends on ammonia made by a reaction Fritz Haber first ran in a laboratory in 1909, and that food is estimated to support nearly half the people alive. The same man personally directed the release of chlorine gas at the Second Battle of Ypres, an operation that produced more than 67,000 casualties, and on 2 May 1915, the night after he oversaw the first chlorine attack, his wife shot herself in the garden with his service revolver.

Breslau, and a Father He Could Not Please

Fritz Jakob Haber was born on 9 December 1868 in Breslau, Prussia — now Wrocław — into a prosperous Jewish family. His father, Siegfried, was a prominent merchant in dye pigments; his mother, Paula, died three weeks after his birth. A stepmother, Hedwig, and three half-sisters became his close family. His relationship with his father stayed distant and strained for life, a fact worth holding onto: much of Haber's career reads as a demonstration of usefulness to an audience that never quite acknowledged it.

He studied at the Friedrich Wilhelm University in Berlin, at Heidelberg, and at the Technische Hochschule in Charlottenburg, taking his doctorate in chemistry in 1891 with research on piperonal derivatives. A brief and unhappy period in his father's chemical business followed. In 1894 he found his footing in academia at the University of Karlsruhe.

Bread from the Air

The problem he took on was the most consequential in applied chemistry. Nitrogen makes up most of the atmosphere but is nearly inert; plants cannot use it directly, and the world's supply of natural fertiliser was finite and geopolitically fragile. In 1909 Haber became the first chemist to synthesise ammonia from nitrogen and hydrogen gas, driving the reaction with high temperature, high pressure and a catalyst. Carl Bosch at BASF scaled the bench result into industry, and by 1913 the Haber–Bosch process was running at production volume.

The consequences are difficult to overstate. Annual global production of synthetic nitrogen fertiliser now exceeds 100 million tons. Haber had, quite literally, made bread out of air — and, incidentally, freed Germany from dependence on imported nitrates for explosives at the exact moment it went to war.

The Manifesto and the Cloud

Haber's enthusiasm for that war was unreserved. He signed the Manifesto of the Ninety-Three in October 1914, was promoted to captain, and took charge of the Chemistry Section of the Ministry of War. He oversaw the chlorine deployment at Ypres in April and May 1915 in person. He then formulated what is still called Haber's rule, the mathematical relationship between the concentration of a gas and the exposure time required to kill — the quantification of poisoning, treated as an engineering variable.

He never apologised. He defended chemical weapons as a natural step in the history of arms: "The disapproval that the knight had for the man with the firearm is repeated in the soldier who shoots with steel bullets towards the man who confronts him with chemical weapons." From 1919 to 1923, in defiance of the peace, he continued developing chemical weapons in secret, assisting Spain and Russia.

Clara

He had married Clara Immerwahr on 3 August 1901. She was the first woman to earn a doctorate in chemistry at the University of Breslau, and by every account a scientist of real ability; their son Hermann was born in 1902. She was also a women's rights activist and a pacifist, and she grew increasingly depressed as her career disappeared into her marriage. On 2 May 1915, the night after her husband directed the first chlorine attack, she shot herself in the heart with his service revolver. She did not die at once. Hermann, twelve years old, heard the shot and found her.

Haber remarried in October 1917, to Charlotte Nathan. They had two children and divorced in December 1927.

The Prize

The Nobel Committee awarded him the 1918 Chemistry Prize, presented in 1919, for the ammonia synthesis. It was, and remains, one of the most contested decisions in the history of the award; critics including Albert Einstein questioned whether the work could be honoured while its author was fresh from directing gas warfare. Haber's acceptance speech contained an unexpected note of humility about the achievement itself: "It may be that this solution is not the final one. Nitrogen bacteria teach us that Nature, with her sophisticated forms of the chemistry of living matter, still understands and utilizes methods which we do not as yet know how to imitate."

There was a further, ghastly coda. During the 1920s, scientists at Haber's Kaiser Wilhelm Institute developed Zyklon A, a cyanide-based fumigant for grain storage — without his direct involvement. A later variant, Zyklon B, was used in the Nazi gas chambers to murder more than a million Jews.

Why Fritz Is Called a Genius

The claim is about a particular kind of scientific imagination: the ability to see an industrial system where others saw a laboratory curiosity. Fixing atmospheric nitrogen was thermodynamically hostile territory, and the achievement was not merely running the reaction but running it under conditions — heat, pressure, catalysis — that could plausibly be built. Haber's mind worked in continuous scale, from bench to factory to national food supply, and it worked identically on both sides of the moral line: Haber's rule is the same instinct for quantification applied to lethality, converting a battlefield horror into a formula. Very few scientists have altered the planet's carrying capacity. He did, and the historian Daniel Charles summarised the resulting career in the phrase "Between genius and genocide."

The deflations are substantial. The laboratory synthesis was Haber's, but the world-changing part — turning it into industry — was Carl Bosch's engineering at BASF, and the process carries both names for good reason. Haber himself conceded at Stockholm that nitrogen-fixing bacteria had solved the same problem more elegantly than he had, without the pressure vessels. And the chemical-weapons work, however technically expert, was not scientific discovery at all; it was the application of known chemistry to killing, pursued with an enthusiasm he never disowned. Great problem-solver, certainly. Whether great mind is the same thing is a question his life was arranged to make impossible to answer cleanly.

Legacy

The patriotism did not save him. After the Nazis took power in 1933, Haber resigned as director of the Kaiser Wilhelm Institute for Physical Chemistry and Electrochemistry. His conversion to Christianity in 1892 and his service as a captain in the last war counted for nothing: he was exposed to the Law for the Restoration of the Professional Civil Service, which targeted Jewish scientists. He spent his last months in Paris, Spain and Switzerland with severe angina. In January 1934 he accepted Chaim Weizmann's offer of a directorship at the Sieff Research Institute in Mandatory Palestine, and died of heart failure in a Basel hotel on 29 January 1934, aged sixty-five, on the way there. Einstein's eulogy was the truest sentence written about him: "Haber's life was the tragedy of the German Jew — the tragedy of unrequited love." His library went to the Sieff Institute, dedicated as the Fritz Haber Library in 1936; his old institute was renamed for him in 1953.