The spontaneous production of helium in a sealed tube containing radium is plainly a new fact of fundamental importance. Ramsay and Soddy accumulated some of the emanation from radium, and enclosed it in a Geissler tube at low pressure. They obtained new lines which they attributed to the emanation, and they also showed that the spectrum of helium was absent at first, but that it came into being little by little in the tube. According to that, helium must be one of the products of the disintegration of radium.
In support of the preceding results may be mentioned some points noticed by Mme. Curie and me at the beginning of our work. We were struck by the simultaneous occurrence of uranium, radium, and helium in the same mineral. We took 50 kilograms of commercial barium chloride, coming from minerals that did not contain uranium, and submitted it to fractional crystallization to see whether it contained traces of radium chloride. After a prolonged fractionation, the portion at the head, now reduced to a few grams, was not at all radioactive. Hence, barium contains radium only when it comes from uranium minerals. These are the same that contain helium. One might think that there is a relation of cause and effect from the simultaneous occurrence of these three substances.
This rapid summary of the researches on radioactivity serves to show the importance of the scientific movement that has been started by the study of this phenomenon. The results obtained are of a nature to modify the ideas one might have about the invariability of the atom, the conservation of matter and of energy, the nature of the mass of bodies, and the energy spread through space. The most fundamental questions of science are thus brought into the discussion. Apart from the theoretical interest of which they are the object, the phenomena of radioactivity give new means of action to the physicist, the chemist, the physiologist, and the physician.
BIBLIOGRAPHY.
Radiation from Uranium.—Becquerel: Compt, rend., 1896-7, different notes; Mme. Curie: Ibid., April, 1898; Rutherford: Phil. Mag., 47, 109 (1899).
Radioactive Minerals.—Mme. Curie: Compt. rend., April, 1898.
Radiation of Thorium.—Schmidt: Wied. Ann., 65, 141; Mme. Curie: Compt. rend., April, 1898; Rutherford: Phil. Mag., 47, 109 (1899); Owens: Ibid., Oct., 1899.
Radiation of Polonium.—P. Curie and Mme. Curie: Compt. rend., July 18, 1898; Mme. Curie: Rev. Gen. des Sciences, Jan. 30, 1899; Mme. Curie: Compt. rend., Jan. 8, 1900. Thèse de doctorat, June, 1903; Becquerel; Compt. rend., 129, 1230; 130, 979, 1154; Merckwald: Ber. d. chem. Ges., June and Dec., 1902; Becquerel; Compt. rend., April 27, 1903 (α-rays), and Feb. 16, 1903.
Radium.—P. Curie, Mme. Curie and Bémont: Compt. rend., Dec. 26, 1898.
Atomic Weight of Radium.—Mme. Curie: Compt. rend., Nov. 13, 1899, Aug., 1900, July 21, 1902; Thèse de doctorat, 1903; Phys. Ztschr., 1903, p. 456.