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The discovery of radium

Posted in Discoveries, Historical articles, History, Science on Friday, 20 December 2013

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This edited article about science first appeared in Look and Learn issue number 499 published on 7 August 1971.

The Curies, picture, image, illustration

Marie and Pierre Curie with their ‘cauldron’ of liquid pitchblend by Peter Jackson

Marie Curie could not sleep that night. She kept thinking about the liquid she had poured into a small dish, which she then put on a stand of the workbench in the miserable tumble-down shed she and her husband used for a laboratory.

Had the liquid dried into crystals of the mysterious element she was searching for? She could stand the suspense no more.

It was long past midnight. She wakened her husband and together they left their tiny home in the slum quarter of Paris and went back to their laboratory.

“Don’t light the lamp,” said Marie Curie, as they entered and closed the door after them.

From the corner of the room where the workbench stood came a faint blue speck of glowing light. Trembling with excitement, Pierre Curie lit the gas lamp. The speck of light from the dish disappeared. All that could be seen was one-tenth of a gramme, or about one five-hundredth of an ounce, of greyish-white salt-like crystals.

The crystals were a new element that no human being had ever seen before. The Curies decided to call the element radium, from the Latin word radius, meaning a ray, because it gave off rays of light. They had found an element which was to be widely used in industry and medicine. They had made a real breakthrough.

Pierre Curie (1859-1906) was a French scientist, and his wife Marie had been born Marie Sklodowska in Warsaw, capital of Poland, in 1867 and later went to study in Paris at the Sorbonne University.

There she met Pierre, who was a Professor of Physics and in 1895 they married. Pierre was already a famous scientist. Together they studied radio-activity in the element uranium. The year of their marriage had been notable for the discovery of X-Rays by the German, Wilhelm Rontgen. A French scientist named Becquerel had been trying to find out more about these rays using a lump of ore containing the element uranium.

One evening when he finished work he wrapped the uranium ore in a piece of paper and put it in a drawer where there were some photographic plates. These were carefully protected against light by several wrappings of black paper.

Some days later he unwrapped the plates and saw in the centre of each a network of veins as if glow-worms had run across the plate. It was just as though a light had got to the plates and taken a photograph!

But no light could have reached the plates! Then Becquerel remembered the uranium ore. Could it be giving off light. Experiments proved not. The Professor was busy with other things, so left the problem a mystery. Which was where the Curies came in.

As we have seen they were very poor. At that time the only source of uranium ore was a material called pitchblend, produced in Bohemia. The Curies were convinced that the mysterious light-giving substance must be in it, so they scraped enough money together to buy a ton of pitchblend and have it sent to Paris.

For months the Curies worked with the pitchblend, extracting from it every substance it contained. For this, it had to be turned into a liquid then dried to form crystal-like powder.

One November afternoon in 1898, the Curies were left with a tiny quantity of greyish-white liquid – which is where our story began.

After finding radium, the pair started experiments to discover why it should give out rays of light in the dark. They eventually found that radium is an element constantly breaking up and, as it does so, creating energy in the form of light. The breakup was a slow process so very little radium is lost.

The Curies worked out that a speck of radium would take 1700 years to lose half its energy. Then, for thousands of years it would lose still more until it finally became a speck of lead.

The Curies also began to realize that radium’s rays – radiation – could be very dangerous to life. A man exposed to them for any length of time would be killed. But it was found that, properly used, radiation could destroy harmful cells and growths in the human body, such as those causing cancer and certain other diseases.

Radium is very expensive, but, fortunately, only small amounts are needed. For instance, the paint that makes your watch glow in the dark contains only about one five-millionth part of radium.

Pierre Curie’s death in 1906 ended the great partnership, but Marie’s work went on. She succeeded him in his post at the Sorbonne and in 1910 she managed to obtain radium in its pure state. For her work she was awarded a second Nobel prize in 1911, the first having been a joint award with her husband in 1903. She was the first scientist to be awarded two Nobel prizes.

Marie and Pierre had found that in isolating radium they had also isolated another element they called polonium in honour of Marie’s native Poland. Their great work together, studying radiation from radium, the effect of magnetism on the radiations, and calculating the heat created by them, helped lay the foundations of the study of nuclear physics.

Pierre met his death because of an accident, but Marie died as a result of her work. One of the most famous women in the world, she helped make radiology a feature of hospital treatment and never stopped her researches.

But then not even Marie knew the full danger of radioactive substances to the human body. She had been burnt a number of times in the course of her work, and her great life was shortened by disease which was the direct result of radioactivity. Their partnership had another result: a daughter named Irene who also won a Nobel Prize.

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