Nicolas Leblanc

• 1. Introduction

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  Nicolas Leblanc was a French surgeon who found a way to turn ordinary table salt into soda ash. He was born on the 6th of December 1742 and died on the 16th of January 1806. Soda ash is the common name for sodium carbonate, and it was in short supply in his day. Salt, by contrast, was cheap and everywhere. How does a trained surgeon end up solving a problem that chemists had been set as a public challenge? What exactly happens to salt inside a furnace? And why did the reward for his success never reach him in full?

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• 2. Guardian And Surgeon

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  In 1751, a minor official at an iron works in Ivoy le Pré, in the Cher region of France, died and left his young son without a father. The boy was Nicolas Leblanc. He was sent to the town of Bourges to live with Dr. Bien, a close friend of the family. Living under the doctor's roof shaped the boy's ambitions, and he developed an interest in medicine. Bien died in 1759. Leblanc then travelled to Paris and enrolled at the École de Chirurgie, the College of Surgeons. He graduated with a master's degree in surgery and opened a medical practice of his own. His training in the body, not the laboratory, would shape the first decades of his working life.

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• 3. A Duke's Household

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  In 1776, Leblanc married, and the couple's first child arrived three years later. A growing family exposed a problem with his chosen trade. The fees paid by his patients were not enough to support them properly. In 1780, he accepted a post as private physician to the household of Louis Philip II, Duke of Orléans. It was a steadier living than a street practice. It also placed a surgeon inside a wealthy noble household, at the very moment a chemical prize was waiting to be won.

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• 4. The Academy's Challenge

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  In 1775, the French Academy of Sciences announced a prize for a process that could produce soda ash from salt. The Academy's reasoning was practical. It wanted a steady supply of sodium carbonate, which the country badly needed, made from sodium chloride, which cost very little. Years passed before anyone met that challenge. By 1791, Leblanc had succeeded. The prize was awarded to him for a process built on two raw materials, sea salt and sulfuric acid. He also built a plant of his own to put the idea to work.

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• 5. Salt In The Furnace

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  Heat did most of the work in Leblanc's method, which ran in two stages. In the first, sodium chloride was mixed with concentrated sulfuric acid at temperatures between 800 and 900 degrees Celsius. Hydrogen chloride gas bubbled off during this step. What stayed behind was solid sodium sulfate. In the second stage, that sodium sulfate was crushed and combined with charcoal and limestone. The mixture went back into a furnace and was heated again, and the result was soda ash. His own plant eventually produced 320 tons of it each year. The method was later replaced by the Solvay process, and today it is obsolete.

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• 6. Confiscation And Ruin

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  The French revolutionary government seized Leblanc's plant a couple of years after his triumph. It also refused to pay the prize money he had earned. In 1802, Napoleon gave the plant back to him, but he did not return the prize. By then, Leblanc could not afford to run the works. The man who had solved the Academy's puzzle was left with a factory he could not operate and a reward he would never see. He ended his own life with a gunshot to the head.

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• 7. Across The Channel

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  A visitor from England named William Losh traveled to Paris to study how Leblanc's process worked. What he learned crossed the Channel with him. In 1807, the year after Leblanc died, Losh joined Wilson and Bell to open the first alkali works in England to use the Leblanc process. It stood at Walker, in Newcastle upon Tyne.

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