双语·居里夫人的故事 第十一章　伟大的发现

Chapter XI　The Great Discovery

MARIE had been working at the laboratory like any other distinguished student of science. She had a double master's degree and a fellowship and had written a thesis on the magnetization of tempered steel. Still in front of her was the title that the most ambitious of the learned coveted—that of Doctor. To win that, it was necessary to discover something unknown before, to solve an unsolved problem. There were many unsolved problems, some of them might have no solution. A man might work a whole lifetime and at the end find that his time and his life had been thrown away. Nature, as Shakespeare says, has a great gift of “taciturnity.” What, among all things unknown, did Marie choose to try to know?

Pierre was the Head of her laboratory. He was the person whose advice she would take and, moreover, he was a physicist of great knowledge and experience. He would surely be able to suggest something which it was necessary to know, something which would help mankind when known and also lead on to further knowledge. Was there any dark ignorance which blocked some entrancing pathway of the route to knowledge? The two often discussed the question. But one day, turning over the pages of a scientific journal where the latest discoveries were discussed, Marie stopped short at the account of the work of a certain Henri Becquerel which had interested her and Pierre when it first appeared a year before. She read it again. She re-read it with care.

Things which have light in themselves! Things which have never caught light from the sun or even from the stars but which have light in themselves! Interesting? Marie was very interested.

R?ntgen had then recently discovered new rays called X-rays and doctors had used them to look through human skin and see the things it hid. Then Poincaré had wondered if there might not be other rays, perhaps somewhat like X-rays which certain light-carrying bodies give off under the action of light. That question had interested Becquerel and he had studied certain substances to see if he could find those rays, supposing they existed. In studying a rare metal called Uranium, he had come upon something most surprising and most new: the salts of Uranium gave off rays without any contact with light at all; they were spontaneously light giving. No one had ever met such a thing before; no one could understand the strangeness of that light or explain it. Becquerel knew certain things about it: for instance, that a Uranium compound placed on a photographic plate surrounded by black paper, repeated the photograph through the paper and also used the surrounding air to discharge an electroscope. Surprising rays indeed!

Becquerel had discovered the fact that this strange radiation existed in the world. Marie determined to explain it. That should be the subject of her Doctor's thesis. The thing might be as small as it would, but it should not escape her. She would find out what that radiation came from, what was its origin and its cause, what, in fact, was its nature, or simply what it was. To find out what a thing is, is to explain it.

There were no books to refer to, except Becquerel's paper which had not gone far into the problem. Nobody in the world knew anything about her subject, so she could have no teacher. She was in for a wild adventure into an unknown world.

But just as an explorer, who plans to penetrate into the secrecy of the Brazilian forest, needs a ship to take him to the Amazon, so Marie needed a room in which her experiments could begin. It was not easy to find. Pierre enquired among his friends. But no one could think of anywhere suitable that was not used for something more important. Perhaps, suggested the Director of the School of Physics, the old storeroom on the ground floor would do. It was the home of spiders and their webs and cluttered up with machines and stores, but there was floor space.

In that odd corner, Marie installed herself. She was fortunately well accustomed to discomfort. In the winter she had to content herself with 11 degrees above freezing point. It didn't matter for her, but her instruments were more delicate and were apt to go wrong when they had to put up with hardships. They made difficulties when damp poured out of the walls and they needed an even temperature. Electrometers are highly sensitive things. Marie had to take their humours into consideration and make allowances for them.

So she began with her Uranium rays. What she had to do was to measure a certain capacity of theirs. She had to find out just how able they were to force the air to carry electricity and just how long it took them to discharge the charge of an electroscope.

Her electroscope was a metal case with two holes in its side. In it a vertical brass strip B was attached to a block of sulphur SS inside the lid—a good insulator. Joined to the strip B was a horizontal wire, ending at one end in a knob C and at the other in a condenser plate P'. Also attached to the strip B was a strip of gold leaf L. The metal case was connected to earth. A charge of electricity was given to the electroscope and then a substance to be tested was placed on a condenser plate P attached to the outer case. That substance would give conductivity to the air between plates P and P' and the charge of the electroscope would begin to leak away. As it leaked, the gold leaf L would fall gradually.

Marie watched what was happening through a miscroscope and a hole in the case. The time taken by the gold leaf to fall was in proportion to the strength of the Uranium rays. In a few weeks, she had become quite sure that the radio-activity of her Uranium the power of the rays—was in proportion to the quantity of pure Uranium in the specimens she placed on P and that it was not affected by the chemical make-up of the specimens or by light or temperature or anything outside itself. It was, so to speak, a very independent character, very much itself. What was it?

She could get no further in her investigation of this strange radiance by studying Uranium. Per-haps, she thought, this tiny, independent original character lives in something else besides Uranium? No one had ever found it elsewhere, but that was no reason for saying that no one ever would. Marie could but look. She determined to examine every known chemical substance. What a determination that was! Every known…!

And, in addition to every known chemical substance, there was a husband to be looked after and a house, and Irène to be dressed and fed and played with and taught. But Marie Curie knew all about work. A guess had floated into her mind, a guess that might have floated into anybody's mind, but hadn't, the guess that if Uranium gave light of itself, surely, in the great universe, there were other substances that did the same thing.

Yes, there were. Marie found another called Thorium. It was then that she gave the name radio-activity to this spontaneous giving out of light.

So she had gone through all the chemical substances known, those substances which, combined in myriads of different ways and proportions, make up the whole world. Two of them were radioactive; but why? What, indeed, was the explanation of their strange and beautiful power? She seemed no nearer to the explanation she sought, and what else was there to do when she had been through all known chemical substances.

Well, there were all the things in the world, in finished articles. Marie had a delicious gift of curiosity. She decided to go to the museum and start on the minerals. Those that contained Uranium or Thorium would be radio-active, of course, and those that had neither of the two would be inactive. Other people had recorded what the minerals were made of; Marie had only to take their records and begin with those that were suspect, with those, that is, which were related to the minerals containing Uranium or Thorium.

When she found an active mineral, she measured the amount of Uranium in it and the same for Thorium and then the radio-activity of the whole. One and one should have made two, but they made eight!

1+1=8 ! ! !

The radio-activity of the mineral she was examining was much stronger than the radio-activity of the Uranium and Thorium in it. Yet she knew by experiment that that was impossible. She had to do her experiments over again, because there must have been a mistake.

If there had been a mistake, she had made it again, because the result was the same. Over and over… and over… and over again, twenty times over, she did her experiment; but the result was always the same.

There could be but one explanation: the minerals must contain, in very small, unperceived quantity, a quite unknown substance which was very much more radio-active than either Uranium or Thorium.

So, in 1898, something existed which was absolutely unknown to man. Marie said to Bronia: “This ray, which I can't explain, comes from an unknown element… it is there; it has only to be found! We are sure of its existence, Pierre and I, but the Physicists, to whom we have spoken of it, think we have made a mistake in our experiments and advise us to be more prudent. But I am convinced that I am not mistaken.”

Marie was deeply excited; for what might not that unknown element turn out to be? She had written once: “Life is not easy for any of us—what does that matter? We must persevere and have confidence in ourselves. We must believe that our gifts are given to us for some purpose and we must attain to that purpose whatever price we may have to pay for it.”

On April 12th, 1898, Marie Curie published the formal statement: “Pitchblende and Chalco lite are much more radio-active than Uranium itself. This fact is very remarkable and leads us to believe that these minerals may contain an element which is much more active than Uranium...”

She believed in the new element, but she had to see it, to be able to show it to men's eyes. Pierre Curie, who up to that moment had been keenly interested in his wife's work and had constantly discussed it with her, gave up his own work and turned to labour side by side with her in the effort to bring to the light of day that hidden, secret element. Two minds and four hands were thence-forth going to fight the tiny thing. Marie had discovered that there must be the element. That was her share. After that she and Pierre shared equally in all the work to be done.

They chose a pitchblende to study because it was four times more active than the Uranium which it contained. Yet all the elements of pitch-blende were well known to all scientists. The unknown must, they argued, be very small to have escaped the notice of careful scientists. It might be a hundredth part of pitchblende, they suggested. What would they have thought at the outset of their work if they had guessed that it was only a millionth part?

They began to break up pitchblende into its elements and to measure the radio-activity of each separate element. As they worked, it became evident that radio-activity dwelt in two chemical fractions of pitchblende; there were two unknown substances. In July, 1898, they found one of the two.

“You must name it,” said Pierre to Marie.

Thoughts flashed through her mind. The discovery would be famous, it would be written about in all countries, therefore she would call it after her oppressed country, Poland. The fierce oppressors should know that Poland could give gifts to the world. She whispered to Pierre the substance's name: “Polonium.”

Then she went home to make fruit jelly, to wash and dress Irène, to write down the baby's weight in a diary and to record that she was cutting her milk teeth, that she could also make a sign with her hand to mean “thank you” and that she could say “gogli, gogli, go!”

But the time for holidays had come. Polonium and the unknown—that other one—were left in the damp laboratory and the baby, the bicycles and the scientists took train for the high hills of Auvergne. Among the little towns with their great cathedrals, their strange, spiked hills crowned with ancient chapels, their extinct volcanoes, two people walked and talked of that other, that something which no man or woman had seen. They looked from Clermont to the flat hill where the first French hero, Vercingetorix, had taught invincible Caesar the bitter taste of defeat. They walked in the town where Bertrand du Guesclin lay buried, he who had first made France feel she was a nation. They watched from the heights one of the most ancient roads go by, the “tin road” along which the Phoenicians had carried tin from uncivilized Britain to the cultured East. All past history seemed alive around them and in their minds, like a little restless star, twinkled the thoughts of that unknown and future thing whose power is still a mystery for us all.

In the autumn, the three Curies returned to work: Irène to produce more teeth and to learn to walk on two feet instead of four paws; and her father and mother to seek the stranger in the damp laboratory.

On December the 26th, 1898, in a paper for the Academy of Science, they announced quite quietly: “The new radio-active substance contains a new element to which we propose to give the name Radium… the radio-activity of Radium must be enormous.”