‘The Scientific History Of Radium’


Marie Curie was born Maria Sklodowska on
7 November 1867 in Warsaw, Poland. She became famous for her research into radioactivity and was the first woman to win a Nobel Prize.
Her family valued education but women could not attend university in Russian-dominated Poland. In 1891, she went to Paris to study mathematics, chemistry and physics at the Sorbonne, adopting the name Marie, and was the first woman to teach there. She met Pierre Curie, professor of physics. Marie and Pierre married in 1895 and for many years this remarkable partnership worked on radioactive substances.
Searching for the source of radioactivity, a word coined by Marie, the Curies discovered two highly dioactive elements, radium and polonium (the latter named after Marie’s Polish origins).
They won the 1903 Nobel Prize for physics for their discovery, sharing the award with another French physicist, Antoine Henri Becquerel (1852-1908), who had discovered natural radioactivity. In 1906, Pierre was run over by a horse-drawn wagon and died. Marie, alone with two small daughters to bring up, took his place as professor of physics, the first woman in the post.
Marie Curie continued her work on radioactive elements and in 1911, won her second Nobel Prize, for isolating radium and studying its chemical properties. In 1914, she helped found the Radium Institute in Paris and was its first director. When World War I broke out, Marie Curie, who promoted the therapeutic properties of radium and its usefulness in destroying cancerous cells, realised that X-rays would help to locate bullets and facilitate surgery. She invented X-ray vans to send out to wounded soldiers.
Marie Curie was quiet, dignified and unassuming and admired by scientists everywhere.
Her work is recorded in numerous papers in scientific journals, and reflected in many awards. In addition to the two Nobel Prizes she also received, jointly with her husband, the Davy Medal of the Royal Society in 1903. In 1921, President Harding, on behalf of the women of America, presented her with one precious gram of radium for her Institute, more  than a hundred thousand times dearer than gold’.
Although used to the publication of learned papers, Marie rarely gave speeches. This one, delivered in 1921, describes the history and significance of her scientific discoveries, characteristically paying tribute both to Pierre and to the work of other scientists who preceded them.
In 1934, at the age of 67, Marie Curie died of leukaemia, probably caused by exposure to the high levels of radiation involved in her research. After her death the Radium Institute was renamed the Curie Institute in her honour. Her daughter, Irene Joliot-Curie became one of the twentieth century’s foremost chemists.
I could tell you many things about radium and radioactivity and it would take long time. But as we cannot do that, I shall only give you a short account of my early work about radium. Radium is no more a baby, it is more than twenty years old, but the conditions of the discovery were somewhat peculiar, and so  it is always of interest to remember them and to explain them.
We must go back to the year 1897. Professor Curie and I worked at that time in the laboratory of the school of Physics and Chemistry where Professor Curie held his lectures. I was engaged in some work on uranium rays which had been discovered two years before by Professor Becquerel.
I spent some time in studying the way of making good measurements of the uranium rays, and then I wanted to know if there were other elements, giving out rays of the same kind. So I took up a work about all known elements, and their compounds, and found that uranium compounds are active and also all thorium compounds, but other elements were not found active, nor were their compounds.
‘What is considered particularly important is the treatment of cancer.’
Then I took up measurements of minerals and I found that several of those which contain uranium or thorium or both were active. But then the activity was not what I could expect, it was greater than for uranium or thorium compound like the oxides which are almost entirely composed of these elements.
Then I thought that there should be in the minerals some unknown element having a much greater radioactivity than uranium or thorium. And I wanted to find and to separate that element, and I settled to that work with Professor Curie. We thought it would be done in several weeks or months, but it was not so. It took many years of hard work to finish that task. There was not one new element, there were several of them. But the most important is radium, which could be separated in a pure state.
Now, the special interest of radium is in the intensity of its rays which are several million times greater than the uranium rays. And the effects of the rays make the radium so important. If we take a practical point of view, then the most important property of the rays is the production of physiological effects on the cells of the human organism. These effects may be used for the cure of several diseases. Good results have been obtained in many cases. What is considered particularly important is the treatment of cancer. The medical utilisation of radium makes it necessary to get that element in sufficient quantities. And so a factory of radium was started to begin with in France, and later in America where a big quantity of ore named carnotite is available. America does produce many grams of radium every year, but the price is still very high because the quantity of radium contained in the ore is so small. The radium is more than a hundred thousand times dearer than gold.
But we must not forget that when radium was discovered, no one knew that it would prove useful in hospitals. The work was one of pure science. And this is a proof that scientific work must not be considered from the point of view of the direct usefulness of it. It must be done for itself, for the beauty of science, and then there is always the chance that a scientific discovery may become like the radium a benefit for humanity.
The scientific history of radium is beautiful. The properties of the rays have been studied very closely. We know that particles are expelled from radium with a very great velocity near to that of the light. We know that the atoms of radium are destroyed by expulsion of these particles, some of which are atoms of helium.
And in that way it has been proved that the radioactive elements are constantly disintegrating and that they produce at the end ordinary elements, principally helium and lead. That is, as you see, a theory of transformation of atoms which are not stable, as was believed before, but may undergo spontaneous changes.
“There is always a vast field left to experimentation and I hope that we may have some beautiful progress in the following years. It is my earnest desire that some of you should carry on this scientific work and keep for your ambition the determination to make a permanent contribution to science.