Attempts at the Artificial Transmutation of Mercury into Gold

E. V. Shpolsky.

In the spring of 1924, news entered the general press that Miethe (A. Miethe), in collaboration with Stammreich (H. Stammreich), had succeeded in effecting the transmutation of mercury into gold, in quantities accessible to chemical analysis. This news was then confirmed in a number of articles by Miethe. In the summer of 1925, reports were published by Nagaoka (H. Nagaoka), who likewise asserts that he succeeded in transforming mercury into gold, under conditions somewhat different from those under which Miethe’s experiments had been carried out.

At the present time a sufficient number of facts has already accumulated to permit certain conclusions to be drawn as to how far the conclusions of Miethe and Nagaoka correspond to reality.

The transmutation of mercury into gold, observed by both investigators, took place under electric discharges. In principle, an electric field alone can cause the disintegration of a nucleus. Indeed, let us have an atom with atomic weight \(A\) and ordinal number \(Z\); its nucleus is built of \(A\) protons and \(A - Z\) electrons. If such a nucleus is placed in an intense electric field, the protons and electrons must be displaced in opposite directions, and, in a sufficiently intense field, the nucleus may be destroyed. Of course, for this fields of many millions of volts per centimeter are necessary.

Nagaoka also relies on a number of other considerations concerning especially heavy elements. The study of the structure of spectral lines has shown that the lines of elements close in the periodic system to the radioactive ones, generally speaking, possess a fine structure. Such are the spectra of bismuth, lead, thallium, and mercury. Nagaoka studied in detail the spectra of thallium and mercury and came to the conclusion that the intervals between the satellites in these spectra can be explained if one assumes that in the nucleus there is a proton quasi-elastically bound to the center of the nucleus. Proceeding from ideas of this kind, Nagaoka attempts to explain the fine structure of non-serial mercury lines by the isotope effect. It should be noted that Rutherford too arrived at the idea of protons—satellites of the main mass of the nucleus—on the basis of his experiments on the artificial disintegration of elements by \(\alpha\)-particles1.

But if this is so, then tearing such a satellite-proton away from the main mass of the nucleus requires the expenditure of considerably less energy than the destruction of the whole nucleus. Recalling that mercury and gold are situated next to one another in the periodic system, Nagaoka comes to the conclusion that their transmutation into one another should be possible with fields accessible to modern laboratory technique.

Finally, there is perhaps an even easier path for the transmutation of mercury into gold (Soddy [7]). The diminution of the nuclear charge by one positive unit, necessary for such a transmutation, can be effected by introducing into the nucleus one electron from outside. It is quite understandable that this electron need possess only such an acceleration as would allow it to pass through the repulsive field of the like-charged outer electrons of the atom; thereafter it enters the attractive field of the nucleus, which inevitably captures it.

The first observations of Miethe were made under the following circumstances.—For his photochemical work, Miethe used a Jae[n]icke mercury lamp. Studying the operation of this lamp together with his assistant Stammreich, Miethe noticed the rapid aging of the lamp under overloads and the appearance of a dark deposit on its walls. Analysis of the residues from the distillation of mercury from old lamps revealed the presence in them of gold, along with many other impurities. The experiment was repeated, the initial mercury being analyzed and, according to Miethe [1], found to be free of gold; the electrodes were likewise examined and also proved to be free of gold. At the end of the experiment gold was found in the mercury. Subsequently Miethe’s collaborator, Stammreich [3], published a detailed protocol of one of the experiments, from which we give below the most essential points. In the quartz that served as the material for the lamp, analysis revealed an insignificant amount of silver \((6 \cdot 10^{-6}\ \mathrm{g}\ \mathrm{Ag}\) in \(14\ \mathrm{g}\) of quartz) and a complete absence of gold. Likewise the electrodes contained an insignificant amount of silver and no gold at all. The mercury for filling the lamp was taken from Kahlbaum and subjected to double slow distillation in vacuo (\(1\ \mathrm{kg}\) per week), after which neither gold nor silver could be detected in it. For the experiment \(1.52\ \mathrm{kg}\) of such mercury was taken. The lamp burned for 197 hours continuously at a current of \(12.6\) amp. and a potential difference of \(160\)—\(175\) volts. At the end of the experiment, gold was found in the mercury in the following amounts: \(1.6 \cdot 10^{-7}\ \mathrm{g}\ \mathrm{Au}\) was detected in droplets that had settled in the form of a ring near the cathode; \(8.2 \cdot 10^{-5}\ \mathrm{g}\)—in the main mass of mercury, and, in addition, a certain amount not susceptible to quantitative determination—in the dark deposit that had settled inside on the quartz tube of the lamp. In further experiments Miethe tested various forms of discharge, and it turned out that gold is also obtained when paraffin is pierced between mercury electrodes and when a sufficiently strong current is passed directly through liquid mercury. It is not uninteresting, however, that Miethe points out that some lamps, when burning steadily for hundreds of hours, gave no gold at all, or almost none, whereas other lamps, even with an unsteady mode of burning, gave in a short time up to \(0.1\ \mathrm{mg}\ \mathrm{Au}\) per kilogram of mercury. Unfortunately, the protocols of the experiments are not given (as in almost all of Miethe’s communications), and the text also does not show whether in these cases the same mercury was used or mercury of different origin.

Nagaoka made his observations not by chance. He was led to the idea of the experimental feasibility of transforming mercury into gold by the study of the fine structure of spectral lines, mentioned at the beginning of this article.

In addition, one phenomenon, observed in connection with an entirely different work, led Nagaoka to the conclusion that, in electrical discharges, fields of colossal intensity can be produced. Studying the arc spectra of metals, Nagaoka discovered in certain lines the Stark effect, indicating the occurrence near the electrode of potential jumps of hundreds of thousands of volts, while the arc was burning at a voltage of the order of 200 volts. This suggested to Nagaoka the idea that, in discharges under high voltage on droplets of mercury, fields of tens of millions of volts per centimeter should be produced.

The experiment was arranged as follows.

Mercury, previously purified by double or triple distillation in a high vacuum at a temperature below \(200^\circ\), was placed in a thick-walled porcelain vessel. The discharge of a large Klingelfuss inductor (spark length in air \(120\ \mathrm{cm}\)) took place between the mercury, the surface of which was covered with paraffin or transformer oil, and a tungsten point; at the same time, in the secondary circuit of the inductor, a large condenser was connected in parallel to the spark gap, and the discharge was carried on continuously for approximately four hours. As a result, the mercury, together with part of the carbonized oil, formed a continuous mass, which was then subjected to further analysis. Initially, ordinary ...

E. V. SHPOLSKY

purely chemical manipulations, which made it possible to extract gold in the form of small granules. Subsequently Nagaoka obtained ruby-colored glass by placing in a crucible fragments of the flask in which the distillation of the mass from mercury and the formation of the alloy had been carried out, and subjecting these fragments to repeated heating to red heat. The ruby glass prepared in this way exhibited the characteristic change of colors, and microscopic examination (at magnifications of 1500–2500 times) made it possible to discover the finest particles of gold.

How reliable are the results of Miethe and Nagaoka? Of course, only repeated repetition of these experiments in various laboratories can give a final answer to such a question. However, as regards Miethe’s experiments, some material is already available. First of all, the possibility of the transmutation of mercury into gold under the weak fields (of the order of \(20 \frac{\text{volts}}{\text{cm}}\)) with which Miethe worked appears highly doubtful. Further, careful investigations by analytical chemists also lead to unfavorable conclusions.

Thus Riesenfeld and Haase [12, 12a] showed that even with very slow distillation gold (which had been specially added to the mercury in a negligible amount) practically always passes into the distillate. Only repeated, careful distillation can, in the authors’ opinion, free mercury from gold completely. Still more interesting are the results obtained by Tiede [13] and his collaborators. Mercury purified by double distillation according to the directions of Miethe and Stammreich did not reveal gold in quantities accessible to chemical analysis. If, however, this mercury, “free from gold,” is distilled once again at a considerably lower pressure and temperature, so that 1 kg of mercury is distilled over the course of 90 hours, then gold can again be detected in the distillate. It is necessary to distill it once more under the same high vacuum and low temperature in order for the gold to disappear completely. With such “completely gold-free” (“Sicherlich weitgehend goldfrei”) mercury, Tiede repeated Miethe’s experiments, but in no case was it possible to obtain gold. From this one may conclude with great probability that the passage of an electric current through mercury in Miethe’s experiments only in some—still not entirely clear—way changes the physical state of the traces of gold present in it, owing to which they become accessible to chemical analysis. Future investigations, which, apparently, will not be long in coming, should finally clarify this question.

Finally, a very important check may be provided by determining the atomic weight of the “synthetic” gold. The point is that the atomic weight of the gold obtained in Miethe’s experiments should be equal to the atomic weight of the isotopes of mercury. These latter atomic weights were precisely determined by Aston [15] only quite recently, and the numbers obtained for them were: 198, 199, 200, 201, 202, and 204. Thus the atomic weight of Miethe’s gold should be no less than 198. Meanwhile, Hönigschmid and Zintl obtained for it \(197.26 \pm 0.2\) [6] (the atomic weight of ordinary gold is 197.2).

All this once again indicates that the gold obtained by Miethe was already present in the mercury he used as his starting material. Nagaoka’s experiments have not yet been subjected to such a careful check; nevertheless, it can already be said in general that if the transmutation of mercury into gold is theoretically quite possible, its experimental realization is a matter of great difficulty.

In conclusion one should also mention the work of Smits and Karssen [14], who attempted to carry out the artificial transformation of lead. For this purpose they built a quartz lamp with molten lead and made this lamp burn at 30–35 amperes and a voltage at the terminals of 80 volts. After ten hours of burning, one could establish the appearance of the brightest lines of the spectrum of mercury, and also characteristic lines of the spectrum of thallium. The authors believe on this

grounds that they had succeeded in observing the transformation of lead into mercury and thallium. From all that has been said above, however, it follows how cautiously one must treat such conclusions.

LITERATURE

1. A. Miethe, Der Zerfall des Quecksilberatoms.—Die Naturwissenschaften, 12, p. 597, 1924.

2. F. Haber, Der Zerfall des Quecksilberatoms. Ibid., p. 633.

3. H. Stammreich, Der Zerfall des Quecksilberatoms. (Weitere Mitteilung.)—Ibid., p. 744.

4. A. Miethe. Gold aus Quecksilber. Zschr. für Techn. Phys. No. 2, 1925.

5. A. Miethe. Gold aus Quecksilber.—Naturwissenschaften, 13, p. 635. 1925.

6. O. Hönigschmidt und E. Zintl. Ueber das Atomgewicht des von Miethe und Stammreich aus Quecksilber gewonnenen Goldes.—Ibid. p. 644.

7. F. Soddy. The Reported Transmutation of Mercury into Gold.—Nature, 113, p. 244, 1924.

8. H. Nagaoka, Y. Sugiura and T. Mishina. The Fine Structure of Mercury Lines and the isotopes.—Japanese Journal of Physics, 2, No. 6—10, p. 121, 1923.

9. H. Nagaoka, Y. Sugiura and T. Mishina. Isotopes of Mercury and Bismuth revealed in the Satellites of their Spektral Lines.—Nature, 113, p. 459, 1924.

10. H. Nagaoka. Die Umwandlung von Quecksilber in Gold.—Die Naturwissenschaften 13, p. 684, 1925.

11. H. Nagaoka. Note preliminaire sur la transmutation du mercure en or.—Journal de Physique et le Radium, 6 (VI), p. 209, 1925.

12. E. H. Riesenfeld und W. Haase. Ueber Herstellung von goldfreiem Quecksilber.—Die Naturwissenschaften, 13, p. 745, 1925.

12a. E. H. Riesenfeld und W. Haase. Über die Destillation von gol-haltigem Quecksilber.—Berichte d. Deutsch. chem. Ges. 30, p. 2828, Dezember 1926.

1. Erich Tiede, Arthur Schleede und Frieda Goldschmidt. Zur Frage der Bildung von Gold aus Quecksilber.—Naturwiss. 13, p. 745, 1925.

2. A. Smits und A. Karssen. Vorläufige Mitteilung über einen Zerfall des Bleiatoms.—Ibid. p. 699.

3. F. Aston. The Isotopes of Mercury. Nature, 113, 1925.

1. Cf., for example, his recent lecture: “Natural and Artificial Disintegration of Elements,” Uspekhi Fizicheskikh Nauk, vol. V, issue 1–2. ↩