Page:Popular Science Monthly Volume 74.djvu/226

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By Professor C. STUART GAGER


THE purpose of the present paper is to present in non-technical form some of the more striking results embodied in the author's memoir on "Effects of the Rays of Radium on Plants."[2]

It is now well known that radioactivity was discovered by Henri Becquerel in 1896. Earlier in this same year Niewenglowski had found that several substances, after being exposed to sunlight, gave off a new kind of rays that could penetrate matter opaque to ordinary light. Following up this work, Becquerel found that the salts of uranium gave off such rays, even when not exposed to sunlight. Uranium, he said, manifests a kind of "invisible phosphorescence." It was Madame Curie who, in 1898, proposed the term "radioactive" for substances possessing this property. In 1898, also, M. and Mme. Curie and Bemont announced the discovery of a new substance fortement radio-active, contained in pitchblende. In a moment of inspiration they named it radium.

The discovery of radioactivity and of radium introduced a new epoch into physical science. Not only was it necessary to revise old ideas and ways of expressing them, but new ideas and conceptions, and a new scientific jargon all developed in less than a decade. Atom, affinity, opaque, ray, electricity, matter and other more or less fundamental terms had to be redefined. To the layman, getting his science largely from the daily press, it was revolution; but to the patient worker in the laboratory it was evolution. He welcomed the new light as the sure reward of years of patient interrogation of nature; as the culmination of a long series of painstaking investigations.

Through the further classical researches of the two Curies, of Rutherford, Righi, Soddy, Becquerel and many others, the new science of radioactivity rapidly developed. The term atom became a figure of speech; matter and electricity became difficult to distinguish from each other, and what remained of scientific materialism received a blow from which it may never recover.

It need hardly be restated here, that radioactivity is an expression of the disintegration of atoms. The atom of radium is constantly breaking up and hurling into space minute particles at enormous

  1. Contributions from the Botanical Department of the University of Missouri. No. 16.
  2. Mem. N. Y. Bot. Gard., 4: 1-286, November, 1908.