Follow-up Q11 (2026-10-08): the "ten thousand times more active" thorium passage

Question (owner, recorded 2026-10-07). Moray's booklet Isotopes in Ionic Recovery of U3O8, pp.4-5, says a metal plate charged with negative electricity at a high potential, placed in a closed vessel with thorium emanation, collects "all the particles emitted by the thorium" and "becomes ten thousand times more active, surface for surface, than the thorium itself" (the question, from memory, gave 1,000 times and a cylindrical device with a charged filament). Is the passage Moray's or copied (Le Bon, or a radioactivity textbook)? What was the original experiment? Does concentrating the deposit add energy, or only raise activity per area? Could Moray have used this to concentrate radioactive products in his tubes (compare the 1968 Air Force proposal)? [Context: the folded metal cylinder that accumulates "emanation", Radiant Energy pp.58-59.]

Web time: about 4 minutes (Chrome: 3 Google searches; curl: Rex Research Le Bon text, Le Moyne Giunta page, two Internet Archive full texts). Stopped early: the question was answered.

What was searched

What was found

1. The passage is Le Bon's, and Le Bon credits Rutherford for the number. Le Bon, The Evolution of Matter (Legge translation, Walter Scott / Scribner, 1909 printing), Book IV, Chapter III ("The Dematerialization of Very Radioactive Substances"), section 6, "Induced Radioactivity": "When, in an enclosed vessel, containing some emanation from a radioactive body --- thorium, for example, a metal plate charged with negative electricity at a high potential is introduced, all the particles emitted by the thorium concentrate themselves upon it, and, according to Rutherford, this plate becomes 10,000 times more active, surface for surface, than the thorium itself" [web https://www.rexresearch.com/lebonmat/lebonmat.htm]. Isotopes booklet pp.4-6 follow this section in order, sentence by sentence, from "It is the emanation which, by freeing itself..." to the lodestone comparison [read: _text Isotopes pp.4-6]. This is the same chapter as the Radiant Energy Rutherford passage (Q01). The booklet does not credit Le Bon in the pages read.

2. What the booklet changed (Rex Research transcription against the booklet's text layer; the Rex text is itself edited, e.g. it inserts "[radon]", so small wording differences may come from the transcription or the printing Moray used): - Both mentions of Rutherford are gone: "Rutherford has verified the fact that the emanations of thorium can pass through water and sulfuric acid" becomes "It has been demonstrated that..."; "according to Rutherford" is dropped, so the 10,000 figure appears unsourced. - "These facts are not ... explicable by the current theory" becomes "... explainable by the electric current theory". Le Bon's "current" means "prevailing" (the electron theory he argues against); the booklet reads it as electric current. Le Bon's "quite inexplicable with the current ideas as to electric particles" appears as "with energy ideas" (a retyping or OCR change; the page image was not checked). - "becoming momentarily radioactive" becomes "becoming radio-active to a lesser or greater degree for various periods of time"; Le Bon's (wrong) sentences "They do not become so if the active salt is enclosed in a glass tube. The beta and gamma rays are alone capable of producing induced radioactivity" are omitted, as is "One really does not see how electricity could bear such treatment". - Added: particles "can remain for weeks in the charged state"; "fifty years ago" before the magnet comparison; Le Bon's "we should have a gas [radon], which ... would be able to circulate in tubes" becomes "we should have particles (which we do not)"; "the so-called electric atoms" becomes "atoms"; "energy" stored in bodies becomes "matter or particles" (already noted in Q04). - The paragraph that follows ("Finally we come to Gamma radiations...") was not found in Le Bon's section; it may be Moray's own.

3. The original experiment is Rutherford's, 1900. Rutherford, "Radioactivity produced in substances by the action of thorium compounds", Phil. Mag. Ser. 5, 49, 161-192 (Feb 1900) [web https://www.physics.mcgill.ca/ Rutherford collection page, citation only; full text not opened]. Rutherford and Soddy (1902): "If the thoria is exposed in a strong electric field, the excited radioactivity is entirely confined to the negatively charged surface. In this way it is possible to concentrate the excited radioactivity on a very small area", removable by acids and left on the dish after evaporation; it halves in about eleven hours [web https://web.lemoyne.edu/giunta/ruthsod.html]. Rutherford's textbook Radio-activity (1st ed. 1904, sec.166; 2nd ed. 1905, sec.176, pp.297-298) gives the apparatus and the number: a metal vessel V holding "a large amount of thoria" is connected to the positive pole of "a battery of about 300 volts"; a wire AB on a rod through an ebonite cork is connected to the negative pole, so "the whole of the excited activity is concentrated upon it. In this way it is possible to make a short thin metal wire over 10,000 times as active per unit surface as the thoria from which the excited activity is derived" [web https://archive.org/details/radioactivity00ruth ; https://archive.org/details/radioactivity00ruthrich]. This is the question's "cylindrical device with a charged filament": a vessel (the positive outer electrode) with a negative wire inside. The number is 10,000, not 1,000, in Rutherford, Le Bon and the booklet. A "one thousand times" does occur in another Le Bon passage that Moray copies (Sea of Energy 4th/5th eds.: "Suppose ... that the dissociation of any substance were only one thousand times more rapid than that of radium...") [read: _text Sea of Energy 5th ed. line 14210], which may be the source of the 1,000 figure in the question (inference).

4. The folded cylinder (Radiant Energy pp.58-59) is also Le Bon's. The Evolution of Matter, experimental part, chapter on dissociation in combustion, near printed p.401: "To cause it to be apparent, it is necessary to compel it to accumulate in a restricted space. It is sufficient for this to fold a sheet of metal so as to transform it into a small cylinder similar to the one which encloses the ball of the condensing electroscope ... left for eight days in darkness ... a discharge of 1 to 2 per minute is obtained" [web Rex Research, same page]. Radiant Energy pp.58-59 copy it, changing "1 to 2 per minute" to "a definite discharge per minute" and adding "or special ray counter instruments" and "also certain gas-filled tubes" [read: _text Radiant Energy 1926 pp.58-59]. This settles the open item in A09 ("Are Radiant Energy pp.58-59 Le Bon's?") for this paragraph.

Reasoning

What the emanation and the deposit are [memory high]. Thorium emanation is thoron, radon-220 (half-life 56 s), a gas that escapes from thoria. It decays (alpha) to polonium-216 (0.15 s), then lead-212 (10.6 h; Rutherford's "eleven hours"), bismuth-212 (61 min), then polonium-212 or thallium-208, ending at stable lead-208. The recoiling daughter atoms are mostly positive ions in the gas, so an electric field drives them to the negative electrode: Le Bon's "particles ... carried along by the air ... attaching themselves like dust". The deposit is real matter (a few billion atoms), which is why acid removes it and it survives evaporation, the fact Le Bon used against the electron theory.

Concentration adds no energy. Each decay releases a fixed energy (Pb-212 to Pb-208 about 11 MeV in all, alphas of 6.05 or 8.78 MeV) [memory medium]. Collecting the atoms on a wire changes where they decay, not how many or how energetic. Total deposit activity is at most the rate at which thoron decays in the vessel, which is less than the thoria's own activity (only part of the thoron escapes the powder). Worked example (illustrative numbers, [memory medium]): 100 g thoria holds 88 g Th-232 at about 4.1 kBq per gram, so 360 kBq per chain member; if 10% of thoron escapes, the wire collects at most about 36 kBq of Pb-212 in steady state. Power: 36,000 per second x 11 MeV x 1.6e-13 J/MeV = 6e-8 W, about 0.06 microwatt, against about 2.4 microwatts for the whole thoria chain (360 kBq x 42.6 MeV). The "10,000 times" is per unit area: a thick thoria layer shows only its top few micrometres (alpha range), a few hundred becquerels per square centimetre at most, while a thin wire of 0.03 square centimetre carrying 36 kBq shows about a million per square centimetre. The gain is geometry: a fraction of the source's output, spread over a small area.

Could Moray have used it in his tubes? Readings, all inference: - A. No deliberate use; he copied Le Bon to argue that radioactivity is "dissociation of matter" and that transmutation is everyday. The booklet uses the passage as an argument against the "electric current theory", not as a design note. Nothing in the pages read describes a negatively charged collector in a device. - B. It happens anyway in any tube with a radioactive coating and a cathode. The patent's tube carries a uranium or carnotite coating (arbiter); carnotite holds radium, whose emanation (radon-222, 3.8 d) leaves a positive-ion deposit on any negative electrode in the gas. A tube run with a negative cathode would plate the active deposit onto it, raising the local ionisation and secondary emission there. That could change a tube's behaviour (easier breakdown, a primed cathode) but adds no energy beyond the source's few microwatts to milliwatts for practical amounts. - C. The 1968 proposal's "low energy excitation, derived from nuclear sources" at "2.5 Mev to 8 Mev" [read: _text 1968 proposal]. That range spans the emissions of the thorium and radium deposits (thallium-208 gamma 2.61 MeV; alphas 6-8.8 MeV) [memory high], so a collected active deposit would be one way to supply it; the proposal does not say how the source is arranged. This match may be coincidence: most alpha emitters fall in 4-9 MeV. - In every reading the energy budget is the source's decay power; the Patent Office's 1932 point (radioactive ionisation gives no space current without a plate potential) still applies.

Open

• The page image of Isotopes p.5 ("energy ideas" vs "current ideas") was not checked.
• Rutherford's 1900 paper (Phil. Mag. 49, 161) was not opened; whether it already gives the 10,000 figure or only the 1904 book does is unknown.
• Which Le Bon printing Moray used (Legge 1907 or 1909); whether any Moray device used a separately biased collector electrode near a radioactive coating. Settled by Moray's notebooks (Mahurin) or by gamma spectroscopy and autoradiography of a surviving tube's electrodes (a lead-212 or radon-daughter deposit decays within days; long-lived lead-210 from radium deposits would remain).

Leads for sites.md

• (follow-up Q11) Isotopes booklet pp.4-6 = Le Bon, Evolution of Matter, Book IV Ch.III sec.6 "Induced Radioactivity", Rutherford credit removed; Radiant Energy pp.58-59 folded cylinder = Le Bon, experimental part (combustion chapter, near p.401).
• (follow-up Q11) Rutherford, Radio-activity (1904 sec.166; 1905 sec.176): 300 V vessel-and-wire apparatus, "over 10,000 times as active per unit surface"; Rutherford, Phil. Mag. 49, 161 (1900).

Corrections to earlier documents

• A09 "open" item "Are Radiant Energy pp. 58-59 Le Bon's?": the folded-cylinder paragraph on p.58 is Le Bon's (Evolution of Matter, near p.401). The orchestrator may update A09 (status wip) accordingly; this agent edits only Q11.