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    "title": "Report, no date",
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        "Safety Light Collection",
        "Records Related to Radium Dial Painters"
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    "ocrText": "16\nPART II.\nTHEORETICAL\nDETECTION OF RADON ELECTROSCOPICALLY. The quantity of radium emanation (radon) in equi-\nlibrium with one gram radium element, called the Curie, has a definite weight and volume.\nIt is one of the fundamental constants in radioactivity. Its volume is 0.663 cubic\nmillimeter, and its weight is 6.5 Radon undergoes spontaneous transforma-\ntion continuously at the rate of-18 per cent per day; or, expressing its transformation\nconstand for the second, we may say that the fraction 2.1 X 10-6 is transformed\nper\nsecond.\nIn considering the quantities of radioactive substances concerned in our measurements we\nhave found it helpful to express the amounts in terms of the actual number of atoms con-\ncerned. In this statistical analysis of our problem let us first deduce the number of\natoms in one curie of radon. This number may be computed from either its weight or\nvolume and the Avogadro number, 6.06 x 1023, designating the number of atoms in the gram\natomic weight of any element. Applied to radon, atomic weight, 222, it means that 222\ngrams of radon contain 6.06 X 1023 individual atoms. Hence the number of atoms in one\ncurie, 6.56 X 10-6 grams, will be given by the equation:\n1.71\n6.06 X 1023 X 6.51 X 10-6 = 59th X 1016\n222\nThis number may also be deduced from radioactive data as follows: The number of\nalpha particles emitted per second by one gram of radium has been determined experimen-\ntally by several investigators, and while the exact value is still in dispute, it will\nan average\nnamely\nsuffice for our purpose to use the value given in the International Critical Tables, namely,\nA\n10\n3.57 x 10\nSince the expulsion of an alpha particle from an atom of radium leaves\none atom of emanation, it follows that 3.57 X 1010 atoms of radon are continually formed\nper second per gram radium, and when equilibrium exists the same number of atoms of radon\nare transformed each second; but in this process of decay only the fraction 2.1 X 10-6\ndisintegrates per second, whence the total number present must be\n3.57 1010\n16\nX\n-\n=\n1.71\nX 10\nfores\n2.09 X 10-6\nen experimental value which checks fairly closely the one deduced from its weight or volume\nand the Avogadro number."
}