Chemistry: Becquerel and Curie
The discovery of radioactivity is probably one of the most significant achievements of human science. This was a rather complicated process and many outstanding scientists worked on this problem. In this respect, it worth to mention Henri Becquerel and Pierre and Marie Curie as probably the most successful researchers in this field. At least, it is possible to estimate that their use of the electroscope contributed significantly to better understanding and detecting radioactive sources.
On analysing their works, it is necessary to point out that Henry Becquerel had actually made a great part of the job concerning the detection of radioactive sources and radioactivity at large but his work could hardly be fully completed without assistance of Pierre and Marie Curie.
In this respect, it should be said that the researches of Becquerel were the continuation of researchers of other scientists, such as Roentgen who discovered X-Ray. Moreover, in his research Becquerel basically followed the general procedure “exploring various types of radiation to perform some of the experiments that Roentgen conducted to determine the properties of X-Rays” (Seaborg 1998, p.199). Basically, Becquerel followed this traditional procedure since he believed that his own rays were similar to those researched by Roentgen.
However, there was a significant difference in his experiments aiming at detection of sources of radioactivity. Notably, he substituted a layer of uranium salts for a cathode-ray tube. Basically he used it in order to show that “the separate gold leaves of an electroscope were made to fall” (Glasstone 1969, p.337). On establishing this electrical property, Henri Becquerel he continued his researches in order to find out whether the rays were reflected and refracted and the conclusion was affirmative.
His further researches with the help of electroscope revealed the fact that uranium nitrate ceases to luminescence when it is dissolved or melted in its water of crystallization and the scientist “in darkness, heated crystal in a sealed glass tube, protecting it even from the light of the alcohol flame” (Crease and Mann 1986, p.276). Than he allowed it to crystallize in darkness. As a result, he found out that “all phosphorescence had been destroyed in this process, yet the salt still produced results on a photographic plate as strong as crystals exposed to light” (Crease and Mann 1986, p.281). On continuing his experiments, he used a disk of pure uranium metal and arrived to the discovery that it produced penetrating radiation three to four time as intense as that he had first seen potassium uranyl sulfate.
Practically at the same time, in parallel research Curie discovered that radiations given of by uranium were composed of more than one type, notably “some rays were bent one way by a magnetic field; others were bent another way” (Spangenburg and Moser 1999, p.402). Actually, scientists knew about this fact but the problem was that nobody exactly knew what these rays, or, to put it more precisely, particles, were composed of, and Curie suggested the name for these radiations – radioactivity – and that is the name that stuck.
Thus, the work of Becquerel and Curie contributed significantly to the research of radiation and was extremely important for the further scientific progress.

1. Badash, Lawrence. “The discovery of radioactivity”, Physics Today, February 1996.
2. Crease, Robert P. and Charles C. Mann. The Second Creation. Affiliated East-West Press Pvt. Ltd. 1986.
3. Spangenburg, Ray and Diane K. Moser. The History of Science from 1895-1945. Universities Press (India) Ltd. 1999.
4. Glasstone, Samuel. Sourcebook on Atomic Energy. Affiliated East-West Press Pvt. Ltd. 1969.
5. Seaborg, Glenn. The Discovery of Radioactivity. New York: New Publishers, 1998.

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