When we think of accidents, we generally think of those that created a lot of damage. The Chernobyl disaster, one of the worst nuclear accidents to ever take place, is one of them. The Bhopal gas tragedy, something that happened closer at home, is another accident that readily comes to our minds. What we don’t do, however, is associate the word ‘accident’ with anything positive. We’ll try and change that today by looking at an industrial process that was discovered by accident — by chance.
Thomas Leopold Willson was born in 1860 in Princeton, Canada. Interest in electricity from an early age allowed him to quit school once his father died in order to try and develop his own arc-lighting systems. With time, he went on to possess a number of patents, but he wasn’t very successful at marketing his ideas.
He set up the Willson Aluminum Company in 1890 to put some of his ideas in place and find an inexpensive way of obtaining pure aluminium. He entered into a partnership with James Turner Morehead, who had surplus waterpower at his disposal in his cotton mill, and set up a plant along the Smith River in California.
Stumbling upon calcium carbideThrough his method of reducing an aluminium ore with carbon in a high-temperature electric furnace, Willson was able to produce only minor quantities of pure aluminium. He reasoned that a more chemically active metal like calcium might come to his aid.
On May 2, 1892, Willson subjected lime (calcium oxide) and coal tar (carbon) to the heat of the arc. The furnace was then tapped (a closed opening at the base of the hearth is drilled open to draw the molten substance after which it is plugged again) to draw the heavy unknown substance that had accidently formed. When this product was thrown into the water, it produced a gas, which burned with a sooty flame.
With time, it was identified that the substance produced was calcium carbide and the flammable gas produced was acetylene. Henri Moissan from France also produced a laboratory method to prepare calcium carbide the same year, but Willson’s process worked out to be cheaper on an industrial scale.
Advantage acetyleneEven though Willson obtained the patents for his process, he had difficulties in promoting the products, be it calcium carbide or acetylene. That changed when acetylene began to be used for lighting, as it could produce a flame that was nearly 10 times brighter than that produced by coal gas.
With the advent of electricity, use of acetylene in lighting homes, railways and mines diminished drastically. Oxyacetylene welding and cutting, a process discovered early in the 20th century, still continues to be used. More importantly, acetylene turned out to be a building block for the synthetic organic chemicals industry, producing hundreds of solvents, plastics and synthetic rubber that are used worldwide.
Reach the writer at ganesh.a.s@thehindu.co.in
