As early as 1899 Pierre Curie succeeded in organizing a first industrial experiment, using for it a chance installation placed at his disposition by the Central Society of Chemical Products, with which he had had relations in connection with the construction of his balances. The technical details had been arranged very successfully by André Debierne, and the operations brought good results, even though it had been necessary to train a special personnel for this chemical work which demanded special precautions.
Our investigations had started a general scientific movement, and similar work was being undertaken in other countries. Toward these efforts Pierre Curie maintained a most disinterested and liberal attitude. With my agreement he refused to draw any material profit from our discovery. We took no copyright, and published without reserve all the results of our research, as well as the exact processes of the preparation of radium. In addition, we gave to those interested whatever information they asked of us. This was of great benefit to the radium industry, which could thus develop in full freedom, first in France, then in foreign countries, and furnish to scientists and to physicians the products which they needed. This industry still employs to-day, with scarcely any modifications, the processes indicated by us.[9]
Even though our industrial experiment yielded good results, again our slender resources made it difficult to make further progress. Inspired by our attempt, a French industrial, Armet de Lisle, had the idea, which seemed daring at that epoch, of founding a veritable radium factory that would furnish this product to physicians, whose interest in the biological effects of radium and its possible therapeutic applications had been aroused by the publication of various investigations. The project proved a success because he could employ men already trained by us in the delicate processes of this manufacture. Radium was then regularly placed on sale, at a high price, it is true, because of the special conditions under which it had to be made, and because, too, of the immediate rise in the cost of the minerals necessary to its production.[10]
I should like to express, here, our appreciation of the spirit in which Armet de Lisle offered to cooperate with us. In an entirely disinterested manner he placed at our disposition a little working place in his factory and a part of the means necessary for us to use it. Other funds were added either by ourselves, or came through subventions, of which the most important, accorded in 1902 by the Academy of Sciences, amounted to 20,000 francs.
It was in this way that we were able to utilize the ore we had acquired little by little in the preparation of a certain quantity of radium, which we used constantly in our research. The radium-bearing barium was extracted in the factory, and I carried on its purification and fractional crystallization in the laboratory. In 1902 I succeeded in preparing a decigramme of chloride of pure radium which gave only the spectrum of the new element, radium. I made a first determination of the atomic weight of this new element, an atomic weight much higher than that of barium. Thus the chemical individuality of radium was completely established, and the reality of radioelements was a known fact about which there could be no further controversy.
I based my doctor's thesis, presented in 1903, on these investigations.
Later, the quantity of radium extracted for the laboratory was increased, and in 1907 I was able to make a second and more precise determination of the atomic weight as 225.35—one accepts now the number 226. I succeeded, too, jointly with André Debierne, in obtaining radium in the state of metal. The total quantity of radium I prepared and gave to the laboratory, in agreement with Pierre Curie's desire, amounted to more than a gramme of radium element.
The activity of pure radium exceeded all our expectations. For equal weights this substance emits a radiation more than a million times more intense than uranium. To offset this, the quantity of radium contained in uranium minerals is scarcely more than three decigrammes of radium to the ton of uranium. There is a very close relation between these two substances. In fact, we know to-day that radium is produced in the minerals at the expense of uranium.
The years that followed his nomination to the P.C.N. were hard for Pierre Curie. He had to face the many anxieties incident to the organization of a complicated system of work when his happiness depended on his being able to concentrate his efforts on a single determined subject. The physical fatigue due to the numerous courses he was obliged to give was so great that he suffered from attacks of acute pain, which in his overtaxed condition became more and more frequent.
It was therefore vitally important, if he was to spare his energy and keep his health, that the burden of his professional duties be lightened. He decided to apply for the Chair of Mineralogy, which was vacant, at the Sorbonne, for which he was entirely qualified because of his profound knowledge and his important publications on the theories of the physics of crystals. Yet his candidacy failed.