Rutherford-Ernest · Source catalogue

A six-page popular account for general magazine readers, with no mathematics. Rutherford describes Becquerel's discovery, the Curies' radium and polonium, and Debierne's actinium, then the three kinds of radiation (alpha, beta, gamma). He calls the alpha rays the important ones: heavy positive bodies at about 20,000 miles a second with a mass he puts at about twice a hydrogen atom, deflected by strong fields in the direction opposite to beta. He attributes the constant warmth of radium (Curie and Laborde: 5 or 6 degrees F above the air) to the alpha particles being stopped inside the radium itself. He pictures the atom as a rotating system of smaller charged parts, one of which escapes with its orbital velocity 'for some reason'. The core is the disintegration theory he and Soddy proposed: radioactive atoms spontaneously change into atoms of other substances. Evidence given: the emanations of thorium and radium (gases of heavy molecular weight, decaying exponentially with half-lives of about one minute and four days, condensing at -120 and -150 C); the 'excited activity' they deposit on surfaces; and the thorium X experiment (ammonia separates a highly active residue from thorium, thorium recovers its activity as thorium X loses it, over about a month, and the cycle can be repeated). He gives a very rough rate for thorium and uranium (about one atom in a million billion per second; a million years for a thousandth part to change) and for radium (life 'not much more than a thousand years'). He reports the Ramsay-Soddy finding that helium appears from radium emanation, and with his own caution says it must be proved that the helium is not from an outside source. He closes with the speculation that all matter may be slowly breaking up, 'per saltum', the converse of Lockyer's view, and that the energy emitted is vastly greater than any chemical reaction but released too slowly to use as power.

Key claims

• Radium stays 5 or 6 degrees F above the air because its own alpha particles are absorbed inside the radium and converted to heat.
• Alpha rays are heavy positively charged bodies of about twice hydrogen mass moving at about 20,000 miles per second.
• Radioactive elements spontaneously disintegrate, and each product is a new kind of matter with its own chemistry (Rutherford and Soddy).
• Thorium continuously makes thorium X at a constant rate; thorium X decays, so thorium's constant activity is an equilibrium of production and decay.
• The radium emanation is a heavy gas that loses half its activity in about four days and that of thorium in about one minute.
• The rate of radioactive change is not altered by temperature from liquid air to red heat.
• Helium is a disintegration product of the radium emanation (Ramsay and Soddy), offered by Rutherford with the reserve that an outside source must be excluded.
• The energy of radioactive change comes from the internal energy of the atom and is enormous compared with any chemical reaction.
• All matter may be slowly breaking up into simpler forms, although most of it too slowly to detect.

Relevance: The earliest and plainest statement in the folder of the disintegration theory, written for non-specialists. It shows what Rutherford claimed and hedged in 1903-1904, before the nuclear atom, and gives the first 'energy is internal, enormous and slow' statement.

Mainstream conflict: None at the time it was written. Later revisions (all [memory], high confidence unless noted): alpha is He2+ with mass about 4, not 2; the rotating-atom escape picture was replaced by the nuclear atom and quantum tunnelling; the rate estimates for thorium and uranium and the radium lifetime were too short; the general claim that all matter disintegrates is not true. Rutherford's own deep-read caveats are in deep/DisintegrationOfTheRadioactiveElements-310cbe.md.

A lay-audience article that takes sides in the long dispute between physics (Kelvin, Helmholtz, Tait) and geology and biology about the age of the earth and sun. Rutherford sets out Kelvin's cooling-earth argument (about 100 million years, later cut to 20-40 million), Helmholtz's contraction argument for the sun (about 40 million years), and Huxley's 1869 reply for the geologists. He then gives his own case: radium emits about 100 calories per hour per gram, one pound in a year giving as much heat as 100 pounds of the best coal; more than three-quarters of that comes from the emanation and its products (his work with Barnes); radioactive matter is found throughout air, water and soil (Elster and Geitel). His calculation: the heat the earth loses by conduction equals that of about 270 million tons of radium, which would be only 5 parts in 10^14 of the earth's mass, 'about' the soil radioactivity observed. The deep read reproduces 270 million tons with a rock conductivity near 1.7 W/(m K) and finds 5e-14 matches the whole earth's mass rather than the crust (the text says 'crust' in one place). If so, Kelvin's assumption of a simple cooling body 'cannot apply' and 'no definite limit can be set' for the earth's age from the temperature gradient. He uses Boltwood's proportionality of radium to uranium to argue uranium is radium's parent, and states that uranium or thorium would be half transformed in about 1000 million years (an estimate, hedged). For the sun he says radium in the proportion of 2.5 parts per million would supply the present output, admits there is no direct evidence of radium in the sun, and then speculates that ordinary atoms may break up at solar temperatures, which would lengthen the sun's life about a hundredfold (to about 5000 million years). He concedes the sun must ultimately grow cold.

Key claims

• One gram of radium gives out about 100 calories per hour, and one pound of radium in a year gives as much heat as about 100 pounds of the best coal.
• More than three-quarters of radium's heat comes from its stored emanation and the products of the emanation (Barnes and Rutherford).
• The earth's present conductive heat loss equals the heat of about 270 million tons of radium, or about 5 parts in 10^14 of the earth's mass, an amount of the order found in soils.
• Radioactive heat can maintain the earth's internal temperature gradient, so Kelvin's cooling-body age of the earth does not apply.
• Radium is a disintegration product of uranium, shown by Boltwood's finding that radium is proportional to uranium in pitchblende.
• Radium in the sun at only 2.5 parts per million of its mass would supply the sun's present output (a power calculation only; no direct evidence of radium in the sun).
• If ordinary elements break up at solar temperatures with radium-like heat, the sun's heat could last about a hundred times longer than the contraction estimate (about 5000 million years).

Relevance: The first application of radioactive heat to earth and sun ages, and the origin of the '270 million tons of radium' figure. It also shows Rutherford separating measured items from conditional inferences and speculations.

Mainstream conflict: The conclusion that radioactive heat undermines Kelvin's age of the earth was later accepted in kind. Later work (mostly [memory]) shows the heat is mainly from long-lived U, Th and K-40 concentrated in the crust, and the sun's energy is nuclear fusion (Bethe 1938), not radium or the breakup of heavy atoms.

The paper that proposes the nuclear atom, though the word 'nucleus' never appears in it; Rutherford writes 'central charge'. Starting from Geiger and Marsden's observation that about 1 alpha particle in 20,000 is turned through about 90 degrees by a gold foil 0.00004 cm thick, he argues that such a deflection must be a single encounter with an intense field, which J. J. Thomson's uniform-sphere atom cannot give. He models an atom with a central charge Ne (Gaussian units, point-like within 10^-12 cm) and an equal and opposite charge spread over a sphere of atomic size. From Coulomb's law he derives the hyperbolic orbit, b = 2p cot(theta), the head-on approach distance b = 2NeE/(mu^2) (3.4e-12 cm for N = 100 and an alpha at 2.09e9 cm/s), cot(phi/2) = 2p/b, and the counting formula y = n t b^2 Q cosec^4(phi/2)/(16 r^2). He predicts the scattered number goes as cosec^4(phi/2), the foil thickness, (Ne)^2, and 1/velocity^4. He compares single with compound scattering and shows single scattering dominates the large-angle tail. He derives the recoil correction for light targets and defers the hydrogen and helium cases. He then fits published data: Geiger and Marsden's platinum back-scatter gives a central charge of 'about 100 e'; Geiger's small-angle gold data give N = 97 and 114; the back-scatter table supports N roughly proportional to atomic weight A for A above aluminium (he notes tin, copper and iron rows that the deep read could not reproduce from the printed numbers). Crowther's beta-ray data cannot separate his theory from Thomson's, and one discriminating test (the shape of I/I0 at small thickness) went against single scattering in Crowther's aluminium data; Rutherford cites Marsden's data and asks for more experiments. He leaves open the sign of the central charge ('independent of the sign'; assumed positive for convenience), atomic stability, possible 'satellites' carrying a small fraction of the charge, and the light-atom cases. He mentions Nagaoka's Saturnian atom as a precedent but does not adopt it, and notes that a gold central charge of about 100e is 'about that to be expected' from 49 helium atoms of charge 2e, 'only a coincidence, but certainly suggestive'.

Key claims

• Large-angle alpha scattering comes from single encounters with an intense central field in the atom, not from the sum of many small deflections.
• The atom has a central charge Ne, concentrated within about 10^-12 cm, and an equal and opposite charge spread through a sphere of radius about 10^-8 cm.
• Alpha particles scattered by a point central charge are distributed in proportion to cosec^4(phi/2), the foil thickness, the square of the central charge, and 1/(alpha velocity)^4.
• The central charge of gold is about 100 electron units (from Geiger and Marsden's platinum back-scatter, and from Geiger's gold data giving N = 97 and 114).
• The central charge is roughly proportional to the atomic weight for atoms heavier than aluminium.
• Electrons in the atom cannot cause large single deflections of an alpha particle.
• The scattering results do not depend on whether the central charge is positive or negative; the sign was not determined in this paper.
• Beta-ray scattering data of Crowther do not distinguish single from compound scattering at the half-scatter point, and his small-thickness curve favoured compound scattering.

Relevance: The founding paper of the nuclear atom and the source of the Rutherford scattering formula, central to the project. It is the primary text; the later books treat it as proven.

Mainstream conflict: None; it is the accepted basis of nuclear physics. The deep read records transcription slips in this web copy (an inverted energy-equation sign, a duplicated silver row in Crowther's table, three z/A^1.5 quotients that do not follow from the printed numbers, 0.0004 where 0.0007 is computed) and that b = 3.4e-12 cm is about 6 percent high by his own constants. N is now the atomic number Z (gold 79), so N = 100 for gold was about 25 percent high [memory, high].

Rutherford's first book: a connected account of radioactive substances written just as the disintegration theory was formed. Chapters: I radioactive substances (uranium, thorium, radium, polonium, actinium); II ionization theory of gases; III methods of measurement (electroscope, electrometer, quartz piezoelectric balance); IV nature of the radiations (alpha, beta, gamma, with deflection experiments and e/m); V rate of emission of energy; VI properties of the radiations (phosphorescence, luminosity, chemical, electrical and physiological effects); VII continuous production of radioactive matter; VIII emanations; IX excited radioactivity; X radioactive processes and theory (including 'causes of disintegration', the Thomson electron-ring radiation hypothesis and the heat of earth and sun); XI radioactivity of the atmosphere and of ordinary materials. The deep read of Chapters V-VII gives the energy accounting. The alpha energy is about 83 times the beta energy per particle (from e/m and speed; arithmetic reproduces 83.3); three methods for 1 g of radium give about 10^11 alpha particles per second and about 50 calories per hour in alpha rays, against the measured heat of about 100 calories per hour (Curie and Laborde 1903; Rutherford and Barnes 65 cal/h per gram of bromide, 110 per gram of radium). The heat tracks the alpha activity: removing the emanation drops it to about 25-30 percent and it recovers in a month, so the emanation and its products supply about three-quarters. Rutherford says the alpha energy explains 'a considerable fraction' but not obviously all of the heat, and allows extra energy from atomic rearrangement. The deep read finds modern decay energies account for the whole observed heat. Chapter VII gives the Ur X and Th X decay-and-recovery experiments, the exponential law I/I0 = e^(-lambda t) and the derivation of equilibrium, the independence of the rate from temperature (red heat to liquid air) and chemical state, the formal disintegration hypothesis, and the magnitude (10^4 to 10^5 thorium atoms per gram changing per second). The digest of Chapter X shows he also lists theories that take radioactive energy from outside the atom (Crookes, the Curies, Kelvin), discusses the detonator analogy, and a Thomson-type radiation-loss cause of disintegration. QE deep read of Chapter X (sec. 199 end-207; printed page = PDF page minus 18 here). Sec. 199-200: Rutherford's case against theories that radium draws its energy from outside: the heat follows the radio-products, more than two-thirds of radium's heat comes from the emanation and emanation X, and 'whenever radio-activity is observed, it is always accompanied by some change' to new products; he gives this as the author and proponent of disintegration [read: p.340]. Sec. 201-203: helium (Ramsay and Soddy 1903, with radium lent by Rutherford); about 1e11 alpha particles per second per gram of radium, 88-90 cubic mm of helium per year, radium half-life about 1500 years on the minimum estimate [read: p.345-351]. Sec. 204: loss of weight; Rutherford allows that weight might change without escape of products 'if gravitation is the result of forces having their origin in the atom'; Heydweiller reported a loss of weight of radium and Dorn a slight indication, 'not confirmed'; Forch saw no appreciable change (sizes not given) [read: p.353-354, page image p.354]. Sec. 205: total heat over radium's life is q/lambda, 2e9 to 5e10 gram-calories per gram ('the minimum estimate is probably nearer the truth'), about a million times any chemical reaction [read: p.354-356]. Sec. 206 (book p.339, PDF p.357): the detonator analogy ('on the same principle that a detonator is necessary to start some explosives') and the gravitation sentence, verbatim: 'It has not been found possible to alter the rate of change of any product by the application of any known physical or chemical forces, unless possibly it is assumed that the force of gravitation which is not under our control may influence in some way the stability of the radio-atoms.' It is a passing possibility with no calculation or experiment attached [read: p.356-357]. J. J. Thomson (Nature, 30 April 1903) suggested that radium's own radiation might drive its disintegration; Rutherford's 1903 test: a few mg of radium bromide, then dissolved in a barium chloride solution at least 1000 times larger in volume, gamma-ray activity measured by electroscope behind 6 mm of lead: 'No appreciable change ... over the period of one month' [read: p.357-358]. This is a single-experimenter, single-run test reported by Rutherford alone. Sec. 207: the sun and the earth. W. E. Wilson's letter (Nature, 9 July 1903): 3.6 g of radium per cubic metre, i.e. '2.5 parts by weight in a million', computed from Curie and Laborde's 100 cal/h per gram and Langley's solar surface emission of 8.28e6 gram-calories per cm2 per hour; G. H. Darwin's gravitational supply of about 12 million years (with Langley's constant); Rutherford's 'from 50 to 500 times longer than was computed by Lord Kelvin', a conditional statement ('if the energy resident in the atoms of the elements is thus available') whose derivation is not shown [read: p.360-362]. Earth heat: X = 3KT/R = 7e-15 cal/s per cc, equivalent to 4.6e-14 g of radium per gram of earth; Elster and Geitel's garden clay gave about 1e-13 g per g, 'about the right order of magnitude' [read: p.362-364]. The book itself gives 876,000 calories per year per gram in sec. 205 and 864,000 in sec. 207 (a 1.4 percent internal inconsistency, immaterial) [read: p.354, p.363].

Key claims

• The energy of one alpha particle from radium is about 83 times that of one beta particle.
• One gram of radium emits about 10^11 alpha particles per second and about 50 gram-calories per hour as alpha-ray energy.
• One gram of radium emits about 100 gram-calories of heat per hour, which is 876,000 per year and comparable per day with the energy needed to decompose a gram of water.
• More than two-thirds of radium's heat comes from the emanation and its products, and the heat follows the alpha activity.
• Ur X and Th X are distinct chemical substances whose activity decays exponentially (half-lives about 22 and 4 days) while the parent's activity recovers at the same rate.
• The rate of decay of radioactive products is not changed by any chemical or physical agency tested, including temperature from red heat to liquid air.
• Radioactivity is the accompaniment of spontaneous disintegration of the atom itself (Rutherford and Soddy); about 10^4 to 10^5 thorium atoms per gram change per second.
• Theories that radioactive energy comes from outside the atom have no experimental support (as the book treats it).
• The gravitation sentence ('the force of gravitation which is not under our control may influence ... the stability of the radio-atoms') and the detonator analogy are already in the 1904 first edition, sec. 206, book p.339.
• Radium bromide dissolved in a solution at least 1000 times larger in volume showed no change of gamma-ray activity over one month (Rutherford 1903), so radium's own radiation does not appreciably drive its disintegration.
• The total heat emitted by one gram of radium over its life is 2e9 to 5e10 gram-calories (minimum estimate favoured), about a million times any chemical reaction.
• Radium at 2.5 parts per million of the sun's mass (W. E. Wilson 1903, from Langley's solar constant) would maintain the sun's heat emission; if ordinary atoms hold a similar store, the sun may last 50 to 500 times longer than Kelvin computed.
• The earth's present heat loss could be maintained by about 4.6e-14 g of radium per g of earth, and garden clay contains about 1e-13 g per g.

Relevance: The first book-length statement of the theory, with the energy calculations and the Ur X / Th X decay-and-recovery experiments. Its chapter on theories (digest only for the full list) sets out the external-energy alternatives Rutherford rejected.

Mainstream conflict: None in kind. Later revisions: alpha has charge 2e, so energy per alpha was about 40 percent low; the 'extra' heat is recoil and beta energy, not a separate source; thorium and uranium atoms decay far more slowly than the 1904 bracket (about 600 times for thorium) [memory, high; deep reader's checks]. Added after QE: the 2.5 ppm solar radium figure is an artefact of Langley's overlarge solar constant (8.28e6 against the modern 5.42e6 cal/cm2/h, a factor 1.53): with Langley's value the radium fraction is 2.53e-6, with the modern value 1.66e-6 [calc, qe.md]. The radium-sun idea, the 50-500 times extension and the weight-loss conjecture were all superseded (solar energy is hydrogen fusion; radium's weight change is the ordinary alpha loss) [memory, high].

Eleven lectures: I historical introduction; II radioactive changes in thorium; III the radium emanation; IV active deposit of rapid transformation; V active deposit of slow transformation; VI origin and life of radium; VII uranium, actinium and the connection between the radio-elements; VIII production of helium from radium; IX radioactivity of the earth and atmosphere (including the earth's heat); X properties of the alpha rays (Bragg curve, e/m, scattering); XI physical view of radioactive processes. The deep reads cover the radium emanation (half-life 3.8 days, decay constant 1/474,000 per second, volume about 0.8 cubic mm per gram, condensing at -150 C, an inert heavy gas) and the heat figures (the emanation and its products give about three-quarters of radium's heat; 25 cal/h and about 9900 cal in total from the emanation and products of 1 g radium). They cover the analysis of the active-deposit decay curves by successive differential equations: radium A (3 min), B (26-28 min), C (19-21 min) and the slow deposit D, E, F (40 years, 6 days, 143 days), with F identified with radiotellurium and polonium and D with radiolead. Rutherford's own footnote admits Schmidt's 1905 finding that radium B is not rayless. Chapter XI gives his view of why atoms disintegrate: he rejects theories that radium takes energy from the surrounding medium on the ground that new substances appear, but states 'it is not yet possible to decide with certainty whether the disintegration is due to an external cause, or is an inherent property of the atom itself', with an external force 'in the place of a detonator' whose energy would still be the atom's own. He prefers a Thomson-style radiation loss governed by probability, with the beta electron as the 'disturbing agent', describes the atom as a swarm of electrons in a positive 'mortar', and cites a Bumstead 1906 result (lead heated more than zinc by X-rays) as suggestive of atomic disintegration brought about by laboratory means. He ends with the speculation that ordinary matter may be undergoing slow transformation, expelling alpha particles below the speed at which they would ionize gas. Added after QE (2026-10-09): the 1906 book says the heating of radium 'is unaltered by plunging the radium into liquid hydrogen' [read: 1906 _text; cited in qe.md C2]. The underlying measurement is P. Curie and Dewar (Proc. Royal Institution, 1904), described in the 1913 book (see that entry). On Bumstead: his 1906 paper (saved at research/pages/archive-amjsci-1906-01.txt) did measure the absorbed fractions with the radiometer, which responds to energy, and found 88 percent absorbed by zinc and 91 percent by lead, against 78 and 79 percent by the electroscope; the factor-two excess heating of lead was therefore not an electroscope-calibration artefact as far as Bumstead could test [read: that page, sec. 8].

Key claims

• The radium emanation is a heavy inert gas with a half-life of about 3.8 days that condenses at about -150 C and obeys the gas laws.
• The active deposit of radium has three rapid successive products A (3 min), B (about 26 min) and C (about 19 min), whose decay curves are fitted by the Bateman-type equations.
• A slow deposit D (about 40 years), E (6 days) and F (143 days) follows radium C, and F is identical with radiotellurium and polonium, D with radiolead.
• One cubic millimetre of emanation from a gram of radium, with its products, releases about 10^7 gram-calories per cubic centimetre, about four million times the heat of burning an equal volume of hydrogen.
• The energy of radioactive change is the atom's own internal energy, not taken from the medium, and may be triggered by internal causes or an unknown external force acting like a detonator.
• The rate of disintegration cannot be altered by temperature (including liquid hydrogen) or chemical conditions, and the decay law expresses probability.
• X-rays on lead may cause atomic disintegration with release of atomic energy (Bumstead; stated by Rutherford as suggestive and needing confirmation).
• Ordinary matter may be undergoing very slow transformation with undetectably weak emission.

Relevance: The fullest account in the folder of the radium chain and how it was untangled, and the book that contains Rutherford's discussion of the cause of disintegration and the external-energy alternatives, relevant to the question of what he meant about control of atomic energy.

Mainstream conflict: None in kind. The deep reader records later changes: radium half-life 1600 years not 1300; D is Pb-210 (22 years); B and C are lead and bismuth isotopes; B does emit beta; the radiation-loss cause of disintegration was superseded by quantum tunnelling; the Bumstead excess-heat result is not now attributed to atomic disintegration (low-medium confidence [memory], needs a web check).

A 19-chapter treatise. The deep reads cover: the theory of successive transformations (Bateman-type solutions, secular and transient equilibrium, with two misprints found in the book: p.444 'b = -lambda1 (lambda2 - lambda1)' and a missing 1/lambda4 in eq. 13); the uranium to ionium to radium chain and its evidence (Boltwood's table of radium proportional to uranium across minerals, 3.4e-7 g radium per g uranium, the missing slow intermediate, half-lives as then known); and Chapters XVIII-XIX on the atom and the earth. On the atom (Ch. XVIII) the book states the nuclear view: a concentrated positive charge of about half the atomic weight times e, carrying most of the mass within about 10^-12 cm, probably built of helium and hydrogen units held by an unknown short-range attraction; instability of the central mass gives alpha particles and of the electron rings gives beta and gamma rays. It records that no laboratory means had changed decay rates, that Rutherford's attempts to make radium by bombarding the emanation, and polonium from lead, were negative, and that radioactivity of potassium and rubidium was known but not shown to be transformation. On the earth (Ch. XIX), radioactive heat is applied: Strutt's measurements show rocks hold about 20 times the radium needed if spread through the whole earth, so activity must be a thin crustal shell or fall with depth. The book states the energy-store claim: 'the total emission of energy for the complete transformation of one gram of radium is about 3.7 x 10^9 calories. There is every reason to suppose that a similar amount of energy is resident in the atoms of the ordinary elements', which if available could lengthen the sun's life. Chapters I-III, V-X, XV-XVI and the rest of XIV are digest only. Deep reads added after QE (2026-10-09). Alpha rays (Chapter IV): Rutherford and Geiger (1908) measured the charge of one alpha particle directly as 9.3e-10 electrostatic units, twice the unit 4.65e-10 the book adopts, so e/m = 5070 matches a helium atom carrying two charges; Regener (1909, scintillations on a diamond) got 9.58e-10, and Rutherford notes a recoil-atom error that would make Regener's too high. Counting (Rutherford and Geiger 1908, Townsend collision ionisation and scintillation calibration): 3.4e10 alpha particles per second from one gram of radium and 13.6e10 from radium in equilibrium with three alpha-emitting products; the 1905 estimate of 6.2e10 rested on an assumed charge of 3.4e-10 and is superseded. Rutherford and Royds (1909): radium emanation sealed in a glass wall under 1/100 mm thick; helium's yellow line in the outer evacuated tube after two days, the whole helium spectrum after six; a control with helium instead of emanation showed none after several days; helium was also found in lead sheet laid over the tube in open air; 'There can thus be no doubt that the alpha particle becomes a helium atom when its charge is neutralised' [read: PDF p.154-156, page image p.155]. The book's own check: 13.6e10 atoms per second is 4.9e-9 cc/s, printed as 158 cubic mm per year (recomputed 154), 'in close agreement' with measured helium production. So the project does hold primary text on alpha = helium at deep-read level, not only at digest level. Heat (Chapter XVII sec. 233-240): P. Curie and Dewar (Proc. Royal Institution, 1904) found radium's heat 'about the same' in boiling carbon dioxide, boiling oxygen and liquid hydrogen, by the volume of gas boiled off in a guarded Dewar flask; the single number given is 73 cc of gas per minute from 0.7 g of radium bromide prepared only 10 days earlier, so the sample was short of equilibrium; no tolerance is stated. The deep reader's plausibility check of that figure is within about 20 percent in order of magnitude (it uses a latent heat from memory). The heat budget in the Vienna standard is 134.4 cal/h per gram of radium in equilibrium: alpha with recoil 123.6 (radium 25.1, emanation 28.6, radium A 30.5, B+C 39.4), beta 4.3, gamma 6.5; Meyer and Hess (1912) measured 132 with all alpha and beta and about 15 percent of the gamma absorbed (like-for-like model value 133.4). Rutherford and Robinson's emanation calorimetry gives 94 observed against 94.5 calculated from the alpha energies; 'the possible absorption or emission of energy due to the rearrangement of the constituents of the atom ... must be small compared with the energy of the expelled alpha particles.' The 2.44e9 cal per gram of emanation is derived in full in sec. 238 and reproduces exactly: 109 cal/h per curie, 0.6 cubic mm per curie, atomic weight 222, so 1.83e7 cal/h per gram, divided by the decay constant 0.0075 per hour. The 3.7e9 cal per gram of radium through radium F is NOT derived step by step in the book: it is stated as 'about one quarter of that due to the emanation and its products ... about 6 x 10^8' for an average alpha-emitting gram, then 'about 3.7 x 10^9' for radium with its products including F, with the method named only as 'the rate of emission and energy of alpha particles, and the period'. The deep reader reconstructs it as about 1.5 times the emanation chain (five alpha particles against three; 29.3 against 19.2 MeV from remembered energies), giving 3.6e9, within 2-3 percent [calc, partly [memory]]. qe.md C3 says the book derives the 3.7e9 in sec. 238; the deep read finds that sec. 238 derives only the 2.44e9, and the 3.7e9 follows from the stated rule and the reconstruction. One anomaly the book leaves unresolved: Poole (1910) measured 500 g of pitchblende and found 8.15e-5 cal/h per gram of mineral, 12.8e-5 per gram of uranium against 7.2e-5 calculated from the alpha energies (about 1.8 times); Poole (1912) found the thorium mineral orangite far above its calculated value; Rutherford suggests 'unsuspected chemical changes in progress in the large mass of mineral'. Pegram and Webb (1908) on thorium oxide agree with the calculation. Tests of temperature and pressure on decay rates (Chapter XIV sec. 200-202): Bronson (1907) found the radium C period (19 min) unchanged after radium B was volatilised off a wire, and gamma activity of radium in a quartz tube unchanged to 1300 C; all observers agree that gamma activity and emanation decay are unaltered up to 1300 C; the conflicting beta-ray results (some saw a temporary rise on heating, some a fall) were traced by Russell (1912) to radium A, B and C redistributing inside the tube and changing the beta absorption in the quartz (volatilisation at 600 C, later revised to about 360 C in hydrogen); Rutherford and Petavel (1907) exploded cordite (about 2500 degrees, about 1000 atmospheres) around radium emanation and saw no change at the moment of explosion; Schuster and Eve and Adams (1907) found gamma activity unchanged at 2000 atmospheres. Rutherford's summary, 'the rate of transformation proceeds at the same rate at a temperature of liquid air -186 as at 1500', cites no experiment for the -186 or 1500 figures in that passage [read: PDF p.527-530]. Transmutation claims (sec. 115-116): Cameron and Ramsay (1907-08) reported neon and argon from emanation acting on water and lithium (with sodium, potassium) from copper salts; Ramsay and Usher claimed carbon dioxide from thorium and zirconium. Rutherford's rebuttals: Rutherford and Royds repeated the water experiment and found only helium, and he attributes the neon and argon to air that 'admittedly leaked into the apparatus' (the passage does not say how air was excluded in the repeat); Mme Curie and Mlle Gleditsch could not confirm the lithium, finding lithium in glass and quartz vessels but not in platinum; Gleditsch and McCoy found no relation of copper, radium and lithium in minerals; for carbon dioxide he argues that organic matter cannot be excluded. Ramsay's own replies are not in these pages. His conclusion: 'so far, no good evidence that the ordinary inactive chemical elements can be transformed by the radiations from active matter' [read: PDF p.343-345]. The sun (sec. 261): the book says a sun of pure uranium in equilibrium would supply 'about one-fourth of the total heat lost by radiation'; the book quotes Langley's solar constant on the same pages, and with Langley's constant instead of the modern one that fraction is 0.30 rather than 0.46 [calc, qe.md C4].

Key claims

• Uranium decays through uranium X, ionium and radium; radium is present in old minerals at 3.4e-7 g per g of uranium.
• The atom has a small massive positively charged centre of charge about half the atomic weight in electron units (as of 1913), with the radius not greater than 10^-12 cm.
• The nucleus is built of helium and hydrogen units bound by an unknown short-range attraction.
• No known physical or chemical agent can hasten or retard radioactive change, and bombardment by alpha, beta or gamma rays had not been shown to make any substance radioactive.
• Complete transformation of one gram of radium releases about 3.7 x 10^9 calories, and a similar store is likely in all atoms.
• Radioactivity of the crust is about 20 times (the book's figure; the deep reader's own check gives about 40) that needed to maintain the earth's heat flow if uniformly distributed, so radioactive matter must be confined to a shell or decrease with depth.
• The sun's age is not limited by Kelvin's contraction argument if atomic energy is available at solar temperatures (speculative; not from known radioactive matter, which would give only a quarter of the sun's output).
• The charge on one alpha particle is 9.3e-10 electrostatic units (Rutherford and Geiger 1908), twice the unit charge, which with e/m = 5070 fits a helium atom with two charges; Regener (1909) found 9.58e-10.
• One gram of radium emits 3.4e10 alpha particles per second, and 13.6e10 per second in equilibrium with its three alpha-emitting products.
• Alpha particles become helium atoms: spectroscopic helium appears in an evacuated tube beyond a glass wall under 1/100 mm thick that only alpha particles from radium emanation can cross (Rutherford and Royds 1909).
• Radium in equilibrium with its products emits 134.4 calories per hour per gram, of which 123.6 is alpha and recoil energy, 4.3 beta and 6.5 gamma; Rutherford and Robinson's emanation calorimetry agrees with the alpha-energy calculation within about 1 percent.
• The heating effect of radium was found 'about the same' in boiling carbon dioxide, boiling oxygen and liquid hydrogen (P. Curie and Dewar, 1904); the one number reported is 73 cc of gas per minute from 0.7 g of radium bromide 10 days old.
• Heating radium to 1300 C, exploding cordite around it (about 2500 degrees, 1000 atmospheres) or pressing it at 2000 atmospheres did not change its decay rate; apparent temperature effects on beta activity were redistribution of the active deposit (Russell 1912).
• Cameron and Ramsay's claimed transmutation of water or copper into neon, argon and lithium was attributed by Rutherford, Curie and Gleditsch to air leaks and to lithium in the glassware; no good evidence existed in 1913 that inactive elements are transformed by radiation.

Relevance: Rutherford's most complete pre-war summary, and the source of the energy-store passage and the denial of any laboratory control of decay as of 1913.

Mainstream conflict: Nuclear charge A/2 was replaced by the atomic number Z; the nucleus as helium and hydrogen units was replaced by protons and neutrons (1932); the sun's energy is not from atomic transformation of heavy matter; the chain was refined (U-234 and protactinium intermediates). All [memory], high. Added after QE: 6.2e10 alpha particles per second (1905) was based on a wrong assumed charge; the book's alpha charge 9.3e-10 is about 3 percent below the modern 2e = 9.61e-10 esu; 3.4e10 per gram is about 8 percent below the modern curie [memory, high]. Poole's pitchblende heat excess is not explained in the book; the book's attribution to chemical changes is Rutherford's suggestion only.

The 1930 successor to the 1913 book, with Chadwick and Ellis. Chapters: I radioactive transformations; II-VI alpha rays; VII general properties; VIII scattering of alpha and beta particles; IX collisions of alpha particles with light atoms; X artificial disintegration of the light elements; XI radioactive nuclei; XII-XIII beta and gamma spectra and disintegration electrons; XIV-XVI passage of beta particles, gamma-ray scattering and intensity; XVII atomic nuclei; XVIII miscellaneous (apparent radioactivity of ordinary matter, potassium and rubidium, scintillation counting, chemistry, radium standards). The deep read (Chapter VIII) reconstructs the Rutherford formula as tested: Geiger and Marsden 1913 verified cosec^4(phi/2) over a 250,000-fold range of counts (5 to 150 degrees, silver and gold; the deep reader notes a 30-50 percent excess at 15-30 degrees in the first data set that the book does not discuss), proportionality to thickness, scattering per atom proportional to A^2 (charge about A/2), and 1/V^4 over a ninefold range (NV^4 constant within about 12 percent). Chadwick's annular-foil method measured nuclear charge as copper 29.3, silver 46.3, platinum 77.4 (atomic numbers 29, 47, 78) to 1-2 percent. Coulomb's law was verified to 3.2e-12 cm for gold, 2e-12 for silver and 1.2e-12 for copper, giving upper bounds on nuclear radii; Rose found no screening effect to 1.7e-10 cm; no departure for any element from copper to uranium. Beta scattering is harder (relativity, spin, radiation, plural scattering); the book states 'an adequate test... has not yet been carried out'. Chapters IX-X (deep read after QE; sections 56-74): the book calculates the Coulomb closest approach of a radium C alpha (7.66 MeV) as 1.9e-13 cm for hydrogen, 1.5 for helium, 5.5 for aluminium, 11.5 for copper, 30.1 for gold (the printed uranium value 38.0e-13 recomputes to about 35e-13; a probable misprint). Departures from Coulomb scattering: hydrogen (Chadwick and Bieler 1921) 100 times the Coulomb count for 8.2 cm alphas at 30 degrees and not quite 4 times for 2.9 cm, with Coulomb holding down to about 4e-13 cm for central and 8e-13 cm for oblique collisions; helium (Rutherford and Chadwick 1927) about 20 times at 40-50 degrees, down to one-third at small angles, Coulomb to 3.5e-13 cm central and about 14e-13 cm glancing; aluminium and magnesium (Bieler 1924; Rutherford and Chadwick 1925) a deficit (to about 0.35 of Coulomb at 135 degrees near 7e-13 cm) and then an unpublished rise to 'several times' at 155 degrees, Coulomb holding to about 13e-13 cm and failing at 6-8e-13 cm. Models offered: an oblate spheroidal alpha particle of semi-axes 8e-13 and 4e-13 cm, later 7e-13 by 2e-13 cm with a proton sphere of 2e-13 cm (Darwin); Bieler's extra attraction proportional to 1/r^4, balancing Coulomb at 3.44e-13 cm; Debye and Hardmeier's nuclear polarisation (1/r^5, polarisability about 0.4e-36 cm^3 for Al and Mg) which fails for helium; the book ends with 'a hitherto unknown ... force' and a 1930 footnote (Mott; Chadwick) saying the alpha's field is spherical and the 'shape' is distortion in the collision. Artificial disintegration: by the long-range proton method boron, nitrogen, fluorine, sodium, aluminium and phosphorus (Rutherford and Chadwick 1921-22); by the right-angle method (1924) also neon, magnesium, silicon, sulphur, chlorine, argon and potassium; 'all the light elements up to and including potassium ... with the exceptions of hydrogen, helium, lithium, beryllium, carbon, and oxygen', always one proton; about 20 disintegrations per million 7 cm alphas absorbed in nitrogen, 8 per million in aluminium, about 1 per million for Cl, Ar and K. Aluminium protons reach 1.37 times the energy of the bombarding alpha, nitrogen absorbs energy, and Al proton energies are not constant from nucleus to nucleus. Blackett (1925): about 23,000 photographs and about 415,000 alpha tracks in nitrogen gave 8 forks with two arms, so the alpha particle is captured and the product is mass 17, atomic number 8; the six measured forks give (energy after)/(alpha energy) = 0.83, 1.02, 0.72, 0.68, 0.88, 0.93, a loss the book states as 19 percent on average (the six ratios average 0.843, a 16 percent loss; the book does not say how 19 was obtained). Other fork reports kept by the book: Auger and Perrin, and Akiyama, found a few collisions that broke energy or momentum conservation; Slater reported gamma rays from gold under alpha bombardment ('cannot be regarded as definite'); the book concludes that in the great majority of collisions both are conserved. Vienna-Cambridge dispute, as stated by the Cambridge authors: 'the Vienna results indicate that the disintegration of an element is a much more frequent occurrence ... Kirsch and Pettersson find that nearly every element can be disintegrated'; 'it seems difficult to put forward any satisfactory explanation', and 'to avoid fruitless discussion' the book reports only Cavendish experiments and gives no Vienna numbers (so the project holds one side's account). Section 74 on transmutation by ordinary means: Miethe (1924-25, mercury to gold in a mercury-vapour lamp), Nagaoka (1925, gold and silver from a discharge in oil), Smits (1926, lead to mercury and thallium; later withdrawn), Wendt and Irion (1922, helium from exploded tungsten wire; Allison and Harkins found none on careful repetition), Riding and Baly (1925, helium and neon from nitrogen under cathode rays; no specific refutation is given) and Paneth and Peters (1926, helium from hydrogen in palladium; withdrawn by the claimants after glass was found to absorb helium from air and release about 1e-9 cc on heating in hydrogen, and a clean repeat gave under 1e-10 cc). The book answers Miethe with Honigschmid and Zintl's atomic weight of 197.2 for his gold and Aston's finding that mercury has no isotope below 198, but itself calls the atomic-weight test 'not conclusive' because the gold was not made by Miethe's process; its conclusion: 'the claims ... of the transmutation of elements by the use of agents other than swift alpha particles are untrustworthy. In all the cases reported the presence of an element has been mistaken for its creation' [read: PDF p.346-349]. Chapter XI (deep read): the opening of section 76 reads, in full, 'The effects of temperatures up to 3000 C., of pressures of 20,000 atmospheres, of powerful electric, magnetic, and gravitational fields have all been looked for, and all in the final analysis without a positive result'; the sentence carries no footnote and no experimenter, date or place is given for any of those tests, gravity included [read: page image p.352]. Radiation as a trigger, all null: Rutherford 1911, radon's decay constant to within 0.05 percent while its concentration fell more than a thousandfold (confirmed by Mme Curie 1924); Danysz and Wertenstein (printed 1925, probably 1915), alpha rays on uranium, not more than 1 alpha in 5 million effective, and on mesothorium not more than 1 in 26,000; Herszfinkiel and Wertenstein (1928), alpha rays on thorium, not more than 1 in 8 million; Hevesy (1922), 800 mg of radium on uranium oxide for six weeks, no change as great as 0.1 percent (not more than 15 in 10^10 absorbed gamma quanta effective), and on radium D under 0.2 percent; Jorissen and Vollgraf (1915), cathode rays on uranium oxide, no change; Walter (1926), 200 kV X-rays on uranium oxide, no change. The uranium paradox: scattering by uranium shows Coulomb's law (Rutherford and Chadwick 1925, parallel to gold at distances 4e-12 to 8e-12 cm; Chadwick, unpublished, 1/v^4 within 5 percent from 3.9e-12 to 6.5e-12 cm), bounding the radius below about 4e-12 cm, yet the energy of the escaping 4.07 MeV alpha requires a radius of at least 6.3e-12 cm (checked: 6.4e-12); 'difficult to reconcile on any theory based on the classical mechanics', but resolved by Gamow and by Gurney and Condon (1928) with barrier penetration (Gamow and Houtermans r0 about 7e-13 cm for the emanations; the book calls the theory 'tentative' and 'not contradicted by any known experimental facts'). Rutherford's 1927 satellite theory of alpha emission (neutral alpha particles in quantum orbits around a core) is listed by the book with three objections of its own: no exponential law or Geiger-Nuttall relation, unspecified difficulties, and no disintegration or non-Coulomb effect when fast alphas hit uranium. Chapter XIII section 93 (the beta-ray energy problem): Ellis and Wooster (1927) measured by calorimetry the energy per radium E disintegration as 350,000 +/- 40,000 volts, matching the mean of the continuous beta spectrum (390,000 +/- 60,000) and 'entirely incompatible' with the 1,050,000 expected if every disintegration released the same energy; Meitner and Orthmann (1930) repeated it and found 337,000 +/- 20,000. Radium B+C ionisation gave about 1e6 volts for the summed mean energies against 2.7e6 for the summed upper limits. The book's statement: 'in a beta ray disintegration the nucleus can break up with emission of an amount of energy that varies within wide limits. No satisfactory interpretation has yet been given of this curious result'; the book names no neutrino, and G. P. Thomson (1929) is cited as questioning energy conservation for each nucleus. The resolution was Pauli's neutrino (1930), Fermi's theory (1934) and detection in 1956 [memory, high]. Pleochroic haloes (book section 38): rings in mica and fluorspar match the alpha ranges of the uranium and thorium series, so the colour record spans geological ages; Joly and Rutherford (1913) estimated that some haloes needed several hundred million years; Joly's 'X' haloes (ranges 1.5-2.25 cm) and Iimori and Yoshimura's 'Z' haloes (1.2-2.1 cm) match no known alpha range and 'their exact origin is unknown'; the inner ring of uranium haloes appeared larger in older micas, for which the book lists a changing decay rate or range (Joly, 'at one time'), extinct short-lived uranium isotopes, radiation damage altering the mica (Lotze; Joly disagrees) and chemistry (Poole), and adopts none. Residual activity of ordinary matter (sections 124-125): in clean metal electroscopes less than 4 ions per cc per second remain; Hoffmann (1920-27) concluded that platinum and brass gave a weak alpha activity 'which could not be attributed to the presence of known radioelements'; Ziegert (1927) traced the brass activity to zinc and separated a residue with three alpha groups of ranges 0.55, 1.15 and 2.05 cm, which the Geiger-Nuttall relation would make extremely slow, inconsistent with the observed rate: 'it is indeed difficult to offer any suggestions as to the source of these alpha particles'; the book concludes 'leaving Ziegert's observations for further investigation' that there is no adequate proof of intrinsic activity in ordinary elements. Potassium and rubidium are the two accepted exceptions (beta only; half-lives about 1.5e12 and 1e11 years); the book assigns potassium's activity to mass 41 (the true isotope is K-40 [memory, high]). Defects the deep readers found in this book: the uranium closest approach (38.0 for 35.2e-13 cm), Blackett's 19 percent against a computed 16, 'Fig. 72' for Fig. 74, '23.0104' in the fluorine mass sum (result consistent), 'cos omega' for sin omega on p.340, a printed 20 MeV barrier height that does not follow from the table's radius (about 33 MeV) and a sentence on Jacobsen's radium C' period that is internally hard to reconcile; none changes a conclusion.

Key claims

• The number of alpha particles scattered per unit area is proportional to cosec^4(phi/2), the foil thickness, the square of the nuclear charge, and 1/(velocity)^4 (Geiger and Marsden 1913).
• The nuclear charge equals the atomic number: measured copper 29.3e, silver 46.3e, platinum 77.4e to 1-2 percent (Chadwick 1920); gold within 2 percent of Z (Rutherford and Chadwick 1925).
• The Coulomb inverse-square law holds for alpha particles and heavy nuclei down to 3.2e-12 cm for gold, 2e-12 for silver and 1.2e-12 for copper, so nuclear radii are smaller than these.
• Beta-particle scattering has not yet been tested strictly against the single-scattering theory.
• Alpha-particle collisions with hydrogen, helium, aluminium and magnesium depart from the Coulomb law: 100 times the Coulomb count for hydrogen (8.2 cm alphas, 30 degrees), about 20 times for helium, a deficit to about 0.35 for aluminium at 135 degrees, with Coulomb holding for central collisions only down to 4e-13 cm (H), 3.5e-13 cm (He) and about 13e-13 cm (Al).
• Alpha particles disintegrate every light element from boron to potassium except carbon and oxygen (lithium and beryllium also give none), emitting one proton each; about 20 per million alphas in nitrogen, 8 per million in aluminium, about 1 per million for Cl, Ar and K (Rutherford and Chadwick 1921-24).
• In Blackett's eight nitrogen forks the alpha particle is captured (two arms only) and the residual nucleus has mass 17, atomic number 8.
• The Vienna workers (Kirsch and Pettersson) reported that nearly every element can be disintegrated with a much higher chance than Cambridge found; the Cambridge authors give no explanation and report no Vienna numbers.
• Claims of transmutation by ordinary means (Miethe, Nagaoka, Smits, Wendt and Irion, Riding and Baly, Paneth and Peters, 1922-26) are, in the book's judgment, 'untrustworthy': two were withdrawn by their authors, one failed a careful repetition, and the book calls the atomic-weight test of Miethe's gold 'not conclusive'.
• No temperature (3000 C), pressure (20,000 atmospheres), electric, magnetic or gravitational field has changed a decay rate (stated without reference in the opening of section 76, gravity included); radiation as a trigger gave only null limits: radon constant to 0.05 percent over a thousandfold concentration change (Rutherford 1911), 1 alpha in 5 million on uranium, 1 in 8 million on thorium, 15 in 10^10 absorbed gamma quanta (Hevesy), plus cathode rays and 200 kV X-rays.
• Calorimetry of radium E gives 350,000 +/- 40,000 volts per beta disintegration, equal to the mean of the continuous beta spectrum and not the 1,050,000 volts of its upper limit, so a beta disintegration releases energy that varies within wide limits (Ellis and Wooster 1927; Meitner and Orthmann 1930: 337,000 +/- 20,000); the book offers no satisfactory interpretation.
• Scattering bounds the radius of the uranium nucleus below about 4e-12 cm while alpha emission energy needs at least 6.3e-12 cm; wave mechanics (Gamow; Gurney and Condon, 1928) removes the conflict by barrier penetration.
• Pleochroic haloes record alpha ranges over geological time; X and Z haloes of ranges 1.2-2.25 cm match no known alpha range and are of unknown origin, and Hoffmann's weak alpha activity in platinum and brass and Ziegert's zinc residue (ranges 0.55, 1.15, 2.05 cm) were left unexplained.

Relevance: The accepted experimental establishment of the nuclear atom and the Rutherford formula, plus the experiments on artificial disintegration and attempts to change decay rates up to 1930. Chapter VIII is the strongest evidence for the project's central scattering claim.

Mainstream conflict: None in kind; nuclear model of 1930 (protons and electrons, no neutron) was replaced in 1932. Defects found by the deep reader in this scan: missing book p.223, footnote year '1921' should be 1911, a minor 1/V^4 table value, a Schonland table with a factor-10 inconsistency, and an effective charge for gold in the Chadwick-Mercier data about 3 below 79. Added after QE: the proton-electron nucleus, the alpha 'shape' (withdrawn in a 1930 footnote), the 'a-prime' particle and the satellite theory were superseded; the H and He departures from Coulomb scattering are the strong nuclear force plus quantum interference [memory, high]; the beta spectrum puzzle was resolved by the neutrino (1930 hypothesis, 1956 detection) [memory, high]; potassium's activity is K-40, not K-41 [memory, high]; the X and Z haloes and Ziegert's short-range alphas were not later confirmed as new elements [memory, medium, not verified]. The Danysz-Wertenstein year 1925 is probably 1915 (Comptes rendus vol. 161) [memory, high for the volume year, medium for the rest; not web-checked].