Central claims: Becquerel-Henri
Source gap (partial). The folder holds three short documents. Only one is by Becquerel: Nature-Feb-1901.pdf (his 1901 review). It has no text layer; the OCR text is good for prose but garbles exponents, so the numbers (Hp = 1600, 1.6 x 10^10, m/e = 10^-7, 4 x 10^-13 emu) come from a page image. The other two are popular articles (R. K. Duncan, Harper's 1902, filed under Becquerel's name; J. J. Thomson, Harper's 1903). Becquerel's original 1896 Comptes Rendus notes and his 1903 Nobel lecture are not in the folder, so the 1896 discovery is known only through his 1901 retelling [read] and the two magazine articles. Obtain those for primary evidence. Alpha = helium nucleus, gamma = electromagnetic radiation, uranium X and radon progeny rest on [memory: high/medium-high] only. The digests contain errors (OCR exponents, who carried radium), so use the deep reads and the text instead.
The sub-claim numbers (2a/2b ... 5a/5b) match the primer's evidence table.
- Uranium and its compounds spontaneously emit a penetrating radiation, with no prior light or heat excitation, that blackens photographic plates and discharges electrified bodies [read: Nature 1901 p.1; Harper's 1902].
- Radioactivity is an intrinsic property of the element, not of phosphorescence or temperature. - 2a. It is bound to the element uranium (metallic uranium is 3-4 times as active as its salts) and shows no appreciable weakening over several years [read: Nature p.1]. (The "independent of chemical form" wording in earlier drafts was wrong; the metal-versus-salt difference is stated in the source.) - 2b. Uranium's activity may be due "in great part, if not altogether" to a small quantity of actinium or another active body (Becquerel's 1901 conjecture, from Crookes's nearly inactive uranium and Debierne and Giesel). Thomson (1903) reports that Becquerel's uranium solution regained all its activity after about twelve months, which supports uranium itself as the source [read: Nature p.3; Thomson, deep read].
- The radiation is a mixture of components. - 3a. A magnetically and electrically deviable part (negative particles; m/e about 10^-7 emu, i.e. e/m about 10^7 emu/g; speed about 1.6 x 10^10 cm/s, about half that of light, for Hp = 1600) that behaves like cathode rays [read: Nature p.3, page image]. - 3b. A non-deviable part, which Becquerel says is "much less penetrating" than the deviable part (polonium-type, stopped by black paper or a few cm of air), plus Villard's separate "very penetrating" non-deviable rays; in modern terms alpha, beta, gamma, though he does not use those names [read: Nature p.2]. The description of the non-deviable part as "like X-rays" is Duncan's (1902) and Thomson's (1903), not Becquerel's.
- The apparently inexhaustible energy output of radium. - 4a. Becquerel's 1901 argument: if the emission is material it loses only about 1 mg per cm^2 per 1000 million years (from a current of 4 x 10^-13 emu per cm^2), so there is "no contradiction" with the absence of an energy source [read: Nature p.3]. - 4b. Mme Curie's speculation (1902) that radium takes energy from radiations traversing all space [read: Harper's 1902]. - 4c. Rutherford and Soddy (via Thomson 1903): the substance continually transforms into forms with less energy, tested by the half-loss/half-recovery equality in thorium X [read: Thomson, deep read]. The energy-budget gap in 4a is several orders of magnitude (up to about 10^5 for pure radium) and is not itself a claim of the source documents; QE flagged that the earlier "10^5" figure assumed pure radium.
- Induced radioactivity. - 5a. Bodies near radium or thorium emanation acquire temporary "induced" radioactivity, concentrated on negatively charged wires and removed by acids, so it is deposited material [read: Nature p.2; Thomson]. - 5b. Thomson (1903) proposed that radioactivity of charged bodies in open air arises from layers of positive ions pulling cathode rays out of the body, with no radioactive substance needed; he gives no data [read: Thomson, deep read]. (Elster and Geitel found the open-air effect; the rain observation is C. T. R. Wilson's.)
Other items from the deep reads that carry no separate claim: radium salts increase in activity after preparation while polonium salts decline [read: Nature p.2]; Giesel's deviable "polonium" was not the Curies' non-deviable polonium; the Curies' products were "several thousand times" uranium's activity in the 1901 article (100,000 is the Harper's figure); Thomson suggests helium may be closely connected with the emanation.