Compound of gold and mercury. Gold from mercury What was in the beginning

Gold and mercury form an amalgam. The formation of this compound is based on the physical properties of metals. Amalgamation was widely used in the technological process for the extraction of a precious component from the rock and for the enrichment of concentrate material.

In Search of the Philosopher's Stone

For many peoples of the world, gold is a symbol of high dignity and value. Quite often in everyday life, characterizing the master, they say that he has golden hands. The definition of black gold in relation to oil has long become customary. As a symbol, this word has become part of proverbs and sayings, and it is customary to celebrate achievements in science and technology with awards made from solar material.

Since the formation of the yellow metal as a medium of commodity exchange, gold has become a symbol of wealth and power. The tireless search for the noble metal led to new geographical discoveries.

The achievements of alchemy, which is called the foolish daughter of chemistry, made it possible to experiment with chemical elements and compounds in search of a philosopher's stone that turns any metal into gold.

The mercury-sulfur theory of the origin of metals developed by alchemists formed the basis of their knowledge. Sulfur and living silver were considered by them as the father and mother of metals. In their activities, alchemists used various metals and substances, each of which corresponded to a symbol or sign.

There are many recipes for obtaining the Philosopher's Stone, but the scientific approach allows you to explain the processes in real time, meaning, and with the understanding that mercury cannot be converted into gold. But it is possible to create an amalgam of solar material with living silver.

Properties of solar metal and mercury

Live silver is a liquid silver-colored metal with a high degree of wetting of other metals. Mercury tends to ball, attracting other particles to it.

This property can be observed in everyday life in case of damage to the mercury thermometer. Small balls of the liquid component rush towards each other and roll into a large moving ball.

Mercury is a heavy chemical element, its specific gravity is only 6 units less than that of gold. Experienced gold miners put liquid silver into sluices designed to wash the slime gold to trap the smallest particles and powder of the precious metal.

The method of obtaining amalgam requires a high purity of gold. It should not be covered with iron, oil or other substances that prevent wetting.

To extract the entire noble component from the concentrate, it should be placed in a dilute 10% solution of nitric acid. In this case, an appropriate vessel for cleaning should be selected in order to avoid the interaction of an acidic environment with the material of the vessel used.

heating the compound until the mercury completely evaporates;
by dissolving living silver in nitric acid.

The temperature at which mercury goes into steam is 357°C. It can be reached in the upper part of the open flame of gas burners. Heating should be carried out in a ventilated area in compliance with safety regulations, and remember that it is dangerous to inhale the vapors of a liquid chemical element.

Solar metal amalgam

Gold in crushed form almost instantly disappears into mercury, being absorbed by the liquid metal. Amalgams, which contain up to 12% of the precious metal, outwardly look like pure living silver.

Therefore, during the flourishing of alchemy, the most popular method for obtaining gold from mercury was to dissolve a small amount of the precious metal and then extract it.

The gold recovery method used in precious metal metallurgy consists of the following technological sequence:

quartz veins containing a precious component are crushed to a fine state;
the powder is washed over copper sheets coated with an amalgam layer;
dusty gold dissolves in the coating layer;
the formed compound is removed from the sheets and subjected to distillation;
the formed ore after the 1st stage of fractionation is treated with a cyanide solution in order to extract the precious component.

In the watch and jewelry industry, to protect products from the effects of atmospheric conditions, gilding is carried out, which is applied by electrolytic and contact methods.

The fire method of gilding, based on the use of gold amalgam, is currently used extremely rarely. This method is based on the ability of solar metal to dissolve in living silver with the formation of an amalgam.

After applying the solution to the surface, the product is heated. As a result of heat treatment, mercury evaporates, and gold remains in the form of a precipitate that adheres tightly to the product.

Mercury can easily dissolve gold, so jewelry made from solar metal should not come into contact with living silver. Even the presence of mercury vapor in the air contributes to the dissolution of the precious metal, which changes its color, becoming white.

Gold amalgam is very concentrated, and if the limit of dissolution of the precious metal is violated, it can break into small pieces. They can be easily collected with a minimal amount of pure mercury, which the small parts of the amalgam will tend to.

Iron does not form compounds with mercury, which allows the use of steel vessels for the transport of raw materials.

Of course, the method of precious metal amalgamation is very toxic and requires precautions. In Russia, in technological processes associated with the enrichment of ores and the extraction of gold from rock, the use of mercury is prohibited by the relevant order.

1. Harbor breakwater? 2. Clothes for bare feet? 3. Tried to get gold from mercury? 4. Copper part of the body? 5. Tenor Domingo? 6. Country and its capital in Africa? 7. A measure of wool from a sheep? 8. A tower from a poet's mouth? 9. Deaf place? 10. Moldovan porridge? 11. Hordes of enemies? 12. Stuffed bumps of life? 13. Man with a spoon? 14. The first stage of haymaking? 15. Athlete with a black belt? 16. Running up the corporate ladder? 17. Matryoshka? 18. Sea pirate? 19. And she herself, and her housing? 20. Panic retreat? 21. Quirinal or Viminal in Rome? 22. Are we talking about a proud bird? 23. Cereal crop? 24. Container for casual purchases? 25. Traveling with a cruise? 26. Stirlitz's name? 27. ... Belshazzar Rembrandt? 28. Ariadne is a diminutive? 29. Incentive...? 30. Large-cheeked flower? 31. What is inserted into the drill? 32. Yes, do they wipe their feet on him? 33. Silent stage of protest? 34. A boat? 35. A puzzle like this one? 36. The act of a burglar? 37. Serf? 38. Fuel for cooking iron? 39. Tobacco of your batch? 40. Harm in response to harm? 41. America's noisiest celebrity? 42. Background for a solo part? 43. Strong heat from fire? 44. A scammer in character? 45. A heating pad for a sore throat? 46. The one who throws money away? 47. Cocking lever? 48. Trauma stuck in hell? 49. Subjugates to his power?

Gold obtained in a nuclear reactor

In 1935, the American physicist Arthur Dempster managed to mass spectrographic isotope determination contained in natural uranium. During the experiments, Dempster also studied the isotopic composition of gold and found only one isotope - gold-197. There was no indication of the existence of gold-199. Some scientists suggested that there must be a heavy isotope of gold, because gold at that time was assigned a relative atomic mass of 197.2. However, gold is a monoisotopic element. Therefore, those wishing to artificially obtain this coveted noble metal must direct all efforts towards the synthesis of the only stable isotope - gold-197.

News of successful experiments in the manufacture of artificial gold has always caused concern in financial and ruling circles. So it was in the time of the Roman rulers, so it remains now. Therefore, it is not surprising that the dry report on the research of the National Laboratory in Chicago by Professor Dempster's group has recently caused excitement in the capitalist financial world: gold can be obtained from mercury in a nuclear reactor! This is the latest and most convincing case of alchemical transformation.

It began as early as 1940, when in some laboratories of nuclear physics they began to bombard with fast neutrons obtained with the help of a cyclotron, the elements adjacent to gold - mercury and platinum. At a meeting of American physicists in Nashville in April 1941, A. Sherr and K. T. Bainbridge from Harvard University reported on the successful results of such experiments. They sent accelerated deuterons to a lithium target and received a stream of fast neutrons, which was used to bombard mercury nuclei. As a result of the nuclear transformation, gold was obtained!

Three new isotopes with mass numbers 198, 199 and 200. However, these isotopes were not as stable as the natural isotope gold-197. By emitting beta rays, after a few hours or days they again turned into stable isotopes of mercury with mass numbers 198, 199 and 200. Therefore, modern adherents of alchemy had no reason to rejoice. Gold that turns back into mercury is worthless: it is deceitful gold. However, scientists rejoiced at the successful transformation of the elements. They were able to expand their knowledge of artificial isotopes of gold.

The "transmutation" carried out by Scherr and Bainbridge is based on the so-called ( n, p) -reaction: the nucleus of a mercury atom, absorbing a neutron n, turns into an isotope of gold and releases a proton R.

Natural mercury contains seven isotopes in different quantities: 196 (0.146%), 198 (10.02%), 199 (16.84%), 200 (23.13%), 201 (13.22%), 202 (29 .80%) and 204 (6.85%). Since Scherr and Bainbridge found isotopes of gold with mass numbers 198, 199, and 200, it must be assumed that the latter arose from isotopes of mercury with the same mass numbers. For example:

198 Hg+ n= 198Au+ R

Such an assumption seems justified - after all, these isotopes of mercury are quite common.

The probability of any nuclear reaction occurring is determined primarily by the so-called effective capture cross section atomic nucleus with respect to the corresponding bombarding particle. Therefore, Professor Dempster's collaborators, physicists Ingram, Hess and Haydn, tried to accurately determine the effective cross section for neutron capture by natural mercury isotopes. In March 1947, they were able to show that the isotopes with mass numbers 196 and 199 have the largest neutron capture cross section and therefore have the highest probability of becoming gold. As a "by-product" of their experimental research, they received... gold! Exactly 35 micrograms, obtained from 100 mg of mercury after irradiation with slow neutrons in a nuclear reactor. This amounts to a yield of 0.035%, however, if the found amount of gold is attributed only to mercury-196, then a solid yield of 24% will be obtained, since gold-197 is formed only from the mercury isotope with a mass number of 196.

With fast neutrons often flow ( n, R)-reactions, and with slow neutrons - mainly ( n, γ)-transformations. The gold discovered by Dempster's employees was formed as follows:

196 Hg + n= 197 Hg* + γ
197 Hg* + e- = 197 Au

The unstable mercury-197 formed by the (n, γ) process turns into stable gold-197 as a result of K-capture (electron from K shells of its own atom).

Thus, Ingram, Hess and Haydn synthesized appreciable amounts of artificial gold in an atomic reactor! Despite this, their "synthesis of gold" alarmed no one, since only scientists who carefully followed the publications in the "Physical Review" learned about it. The report was brief and probably not interesting enough for many because of its uninformed title: "Neutron cross-sections for mercury isotopes" ( Effective cross sections for neutron capture by mercury isotopes).
However, chance would have it that two years later, in 1949, an overly zealous journalist picked up this purely scientific report and, in a noisy market manner, proclaimed in the world press about the production of gold in an atomic reactor. Following this, in France there was a major confusion in the quotation of gold on the stock exchange. It seemed that events were developing exactly as Rudolf Daumann had imagined, who predicted the “end of gold” in his science fiction novel.

However, artificial gold obtained in a nuclear reactor was long in coming. It had no intention of flooding the markets of the world. By the way, Professor Dempster had no doubts about it. Gradually, the French capital market calmed down again. This is not the last merit of the French magazine "Atoms", which in the January issue of 1950 published an article: "La transmutation du mercure en or" ( Transmute Mercury to Gold).

Although the magazine, in principle, recognized the possibility of obtaining gold from mercury by a nuclear reaction, however, he assured his readers of the following: the price of such an artificial precious metal would be many times higher than natural gold mined from the poorest gold ores!

Dempster's employees could not deny themselves the pleasure of getting a certain amount of such artificial gold in the reactor. Since then, this tiny curiosity has graced the Chicago Museum of Science and Industry. This rarity - evidence of the art of "alchemists" in the atomic age - could be admired during the Geneva conference in August 1955.

From the point of view of nuclear physics, several transformations of atoms into gold are possible. We will finally reveal the secret of the philosopher's stone and tell you how to make gold. We emphasize here that the only possible way is the transformation of nuclei. All other recipes of classical alchemy that have come down to us are worth nothing, they only lead to deception.

The stable gold, 197Au, could be made by radioactive decay of certain isotopes of neighboring elements. The so-called nuclide map teaches us this, in which all known isotopes and possible directions of their decay are presented. So, gold-197 is formed from mercury-197, which emits beta rays, or from such mercury by K-capture. It would also be possible to obtain gold from thallium-201 if this isotope emitted alpha rays. However, this is not observed. How to get a mercury isotope with a mass number of 197, which is not found in nature? Purely theoretically, it can be obtained from thallium-197, and the latter from lead-197. Both nuclides spontaneously with the capture of an electron turn into mercury-197 and thallium-197, respectively. In practice, this would be the only, albeit only theoretical, possibility of making gold from lead. However, lead-197 is also just an artificial isotope, which must first be obtained by a nuclear reaction. It won't work with natural lead.

Isotopes of platinum 197Pt and mercury 197Hg are also obtained only by nuclear transformations. Really feasible are only reactions based on natural isotopes. Only 196 Hg, 198 Hg and 194 Pt are suitable as starting materials for this. These isotopes could be bombarded with accelerated neutrons or alpha particles in order to arrive at the following reactions:

196 Hg + n= 197 Hg* + γ
198 Hg + n= 197 Hg* + 2n
194 Pt + 4 He = 197 Hg* + n

With the same success, one could obtain the required platinum isotope from 194 Pt by ( n, γ)-transformations either from 200 Hg via ( n, α) -process. In this case, of course, we must not forget that natural gold and platinum consist of a mixture of isotopes, so that in each case it is necessary to take into account competing reactions. Pure gold will eventually have to be isolated from a mixture of various nuclides and unreacted isotopes. This process will be costly. The conversion of platinum into gold will generally have to be abandoned for economic reasons: as you know, platinum is more expensive than gold.

Another option for the synthesis of gold is the direct nuclear transformation of natural isotopes, for example, according to the following equations:

200 Hg + R= 197 Au + 4 He
199 Hg + 2 D = 197 Au + 4 He

Would also lead to gold-197 (γ, R) -process (mercury-198), (α, R) -process (platinum-194) or ( R, γ) or (D, n)-transformation (platinum-196). The question is only whether it is practically possible, and if so, whether it is cost-effective at all for the reasons mentioned. Only long-term bombardment of mercury with neutrons, which are present in the reactor in sufficient concentration, would be economical. Other particles would have to be obtained or accelerated in a cyclotron - such a method, as is known, gives only tiny yields of substances.

198 Hg+ n= 198 Au* + p
198 Au = 198 Hg + e- (2.7 days)
It is by no means possible to exclude the reverse transformation of radioactive gold into mercury, that is, to break this Circulus vitiosus: the laws of nature cannot be circumvented.

Under these conditions, the synthetic production of an expensive noble metal, platinum, seems less complicated than "alchemy". If it were possible to direct the neutron bombardment in the reactor in such a way that it would occur predominantly ( n, α)-transformations, one would hope to obtain significant amounts of platinum from mercury: all common mercury isotopes - 198 Hg, 199 Hg, 201 Hg - are converted into stable platinum isotopes - 195 Pt, 196 Pt and 198 Pt. Of course, the process of isolating synthetic platinum is also very complicated here.

Frederick Soddy back in 1913 proposed a way to obtain gold by nuclear transformation of thallium, mercury or lead. However, at that time, scientists knew nothing about the isotopic composition of these elements. If the process of splitting off alpha and beta particles proposed by Soddy could be carried out, it would be necessary to proceed from the isotopes 201 Tl, 201 Hg, 205 Pb. Of these, only the 201 Hg isotope exists in nature, mixed with other isotopes of this element and chemically inseparable. Therefore, Soddy's recipe was not feasible.

What even an outstanding researcher of the atom fails, of course, the profane cannot accomplish. The writer Daumann, in his book The End of Gold, published in 1938, gave us a recipe for turning bismuth into gold: by splitting off two alpha particles from the bismuth nucleus using high-energy X-rays. Such a (γ, 2α)-reaction is not known up to now. In addition, the hypothetical transformation

205 Bi + γ = 197 Au + 2α

cannot go for another reason: there is no stable isotope 205 Bi. Bismuth is a monoisotopic element! The only natural isotope of bismuth with a mass number of 209 can give, according to the principle of the Daumann reaction, only radioactive gold-201, which with a half-life of 26 minutes turns back into mercury. As you can see, the hero of Dauman's novel, the scientist Bargengrond, could not get gold!

Now we know how to really get gold. Armed with knowledge of nuclear physics, let's risk a thought experiment: we will turn 50 kg of mercury in a nuclear reactor into full-weight gold - into gold-197. Real gold is obtained from mercury-196. Unfortunately, mercury contains only 0.148% of this isotope. Therefore, in 50 kg of mercury there is only 74 g of mercury-196, and only this amount can we transmute into true gold.

At first, let's be optimistic and assume that these 74 g of mercury-196 can be converted into the same amount of gold-197 if mercury is bombarded with neutrons in a modern reactor with a capacity of 10 15 neutrons / (cm 2 . With). Let us imagine 50 kg of mercury, that is, 3.7 liters, in the form of a ball placed in a reactor, then a flow of 1.16 . 10 18 neutrons. Of these, 74 g of isotope-196 is affected by 0.148%, or 1.69 . 10 15 neutrons. For simplicity, we further assume that each neutron causes the transformation of 196 Hg into 197 Hg*, from which 197 Au is formed by electron capture.

Therefore, we have 1.69 . 10 15 neutrons per second in order to turn mercury-196 atoms. How many atoms is that actually? One mole of an element, i.e. 197 g of gold, 238 g of uranium, 4 g of helium, contains 6.022 . 10 23 atoms. We can get an approximate idea of this gigantic number only on the basis of a visual comparison. For example, this: imagine that the entire population of the globe in 1990 - about 6 billion people - started counting this number of atoms. Everyone counts one atom per second. Count 6 in the first second . 10 9 atoms, in two seconds - 12 . 10 9 atoms, etc. How long would it take humanity in 1990 to count all the atoms in one mole? The answer is staggering: about 3,200,000 years!

74 g of mercury-196 contains 2.27 . 10 23 atoms. Per second with a given neutron flux, we can transmute 1.69 . 10 15 atoms of mercury. How long will it take to convert all of the mercury-196? Here is the answer: it will take an intense bombardment of neutrons from a high-flux reactor for four and a half years! We must make these enormous expenditures in order to eventually obtain only 74 g of gold from 50 kg of mercury, and such synthetic gold must also be separated from the radioactive isotopes of gold, mercury, etc.

Yes, that's right, in the age of the atom you can make gold. However, the process is too expensive. Gold obtained artificially in a reactor is priceless. It would be easier to sell a mixture of its radioactive isotopes as "gold". Maybe science fiction writers will be tempted to make up stories involving this "cheap" gold?

"Mare tingerem, si mercuris esset" ( I would turn the sea into gold if it consisted of mercury). This boastful saying was attributed to the alchemist Raimundus Lullus. Let's assume that we have turned not the sea, but a large amount of mercury into 100 kg of gold in a nuclear reactor. Outwardly indistinguishable from natural, this radioactive gold lies in front of us in the form of shiny ingots. From the point of view of chemistry, this is also pure gold.

Some Croesus buys these bars at what he thinks is a similar price. He does not suspect that in reality we are talking about a mixture of radioactive isotopes 198 Au and 199 Au, the half-life of which is from 65 to 75 hours. You can imagine this miser who saw that his golden treasure was literally leaking through his fingers.

For every three days his property is reduced by half, and he is not able to prevent it; in a week from 100 kg of gold there will be only 20 kg, after ten half-lives (30 days) - practically nothing (theoretically, this is another 80 g). Only a large puddle of mercury remained in the treasury. The deceptive gold of the alchemists!

The history of alchemy is basically the history of finding a way to turn lead or mercury into gold. About the real chemical discoveries that the alchemists of the Middle Ages made along the way, they often talked casually, without much attention. The main thing they were looking for was Magisterium (aka red tincture, panacea of life, life elixir, philosopher's stone) - a certain substance, a reagent that would make it possible to obtain noble metals from base metals.

It is not known for certain whether anyone managed to obtain gold from mercury and lead using a chemical reaction, although there are still many legends about this. However, in the middle of the 20th century, a group of American physicists managed to obtain a small amount of the stable isotope of gold from mercury, but only by means of nuclear physics. The transformation of metals, it is also transmutation, turned out to be possible!

The story began in 1940. Then, in several world laboratories, experiments began to be carried out on the bombardment of mercury, which is adjacent to gold in the Periodic Table of Mendeleev, with fast neutrons. The first successful results of the experiments were announced in April 1941 at a meeting of American physicists in Nashville by Harvard scientists A. Sherr and K. T. Bainbridge.

They managed to obtain three isotopes of gold with mass numbers 198, 199 and 200. But they were not stable and turned back into mercury over a period of several hours to several days.

A way was needed to obtain a natural isotope - gold-197. On this path, although not on purpose, went the staff of the laboratory of Professor Arthur Dempster - physicists Ingram, Hess and Haydn. (Arthur Dempster is known for creating the first modern mass spectrometer and discovering, along with F. Aston, a record number of isotopes of chemical elements).

In March 1947, this group of scientists, in the process of studying the process of neutron capture by atomic nuclei, managed to obtain the desired gold-197 as a by-product. It was "extracted" from 100 milligrams of mercury-196 by irradiating it with slow neutrons in a nuclear reactor.

The yield of sustainable gold was only 35 μg. This, by scientific standards, is quite a tangible amount of artificial gold. The discovery was published in the journal Physical Review. But the general public, of course, did not notice the article entitled "Effective Cross Sections for the Capture of Neutrons by Mercury Isotopes".

However, in 1949, a certain "yellow" journalist published an article about the beginning of gold production in nuclear reactors. The publication resulted in a panic on the French stock exchanges, which led to a collapse in gold prices. The panic stopped only in 1950, when the Atoms magazine published an article "Transmutation of mercury into gold", in which it reported that the cost of producing artificial gold from mercury was many times higher than the cost of extracting natural gold from the most seedy gold ore.

35 micrograms of artificial gold is still kept in Chicago - at the Museum of Science and Industry. Since then, no one has been seriously engaged in the production of gold-197 from base metals and no one has tried to reduce the cost of the technology.

In the 21st century, the unstable radioactive gold-198 is obtained from mercury-198, which is used as a drug for obtaining radiographs of the human body organs (instead of X-rays) and treating cancerous tumors. It turns out that the atoms of such gold work like small X-ray tubes and kill cancer cells in a strictly defined area of the body.

And in the 21st century, "alchemy in reverse" is flourishing. From gold, for example, isotopes of the elements valuable for science, francium and astatine, which simply do not exist in nature, are obtained.

Photo: “Goden eggs in cardboard” (corbisimages.com/photographer/bevis-boobacca), Arthur Dempster (American Institute of Physics)

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For several years already, Adolf Miethe had been coloring minerals and glass under the action of ultraviolet rays. To do this, he used an ordinary mercury lamp - an evacuated quartz glass tube, between the electrodes of which a mercury arc is formed that emits ultraviolet rays.

Later, Mite used a new type of lamp, which gave a particularly high energy output. However, during long-term operation, raids formed on its walls, which greatly interfered with work. In used mercury lamps, such raids could also be detected if the mercury was driven away. The composition of this blackish mass interested the Privy Councilor, and suddenly, when analyzing the remainder of 5 kg of lamp mercury, he found ... gold. Mite pondered: is it theoretically possible that mercury in a mercury lamp, as a result of the destruction of an atom, decays to gold with the splitting off of protons or alpha particles. Mite and his collaborator Hans Stamreich carried out numerous experiments, fascinated by the idea of such a transformation of elements. Mercury distilled in vacuum served as the starting material. The researchers believed that it did not contain gold. This was also confirmed by the analyzes of famous chemists K. Hoffmann and F. Gaber. Mite asked them to investigate the mercury and residues in the lamp. With this mercury, which, according to analytical data, was free of gold, Mite and Stamreich filled a new lamp, which then worked for 200 hours. golden yellow agglomerate of octahedral crystals.

However, Frederick Soddy did not think that gold was formed by splitting off an alpha particle or a proton. Rather, we can talk about the absorption of an electron: if the latter has a sufficiently high speed to pierce the electron shells of atoms and penetrate into the nucleus, then gold could be formed. In this case, the serial number of mercury (80) is reduced by one and the 79th element is formed - gold.

Soddy's theoretical statement reinforced the point of view of Mite and all those researchers who firmly believed in the "decay" of mercury to gold. However, they did not take into account the fact that only one isotope of mercury with a cash value of 197 can turn into natural gold. Only the transition 197 Hg + e- = 197 Au can give gold.

Does the isotope 197 Hg even exist? The relative atomic mass of this element of 200.6, then called the atomic weight, suggested that there are several of its isotopes. F.V. Aston, while studying canal rays, did find mercury isotopes with mass numbers from 197 to 202, so such a transformation was probable.

According to another version, 200.6Au could also be formed from a mixture of 200.6Hg isotopes, that is, one or more isotopes of gold with large masses. This gold should have been heavier. Therefore, Mite hurried to determine the relative atomic mass of his artificial gold and entrusted this to the best specialist in this field - Professor Gonigschmidt in Munich.

Of course, the amount of artificial gold for such a determination was very meager, but Mite did not have more yet: the beetle weighed 91 mg, the diameter of the ball was 2 mm. If we compare it with other "yields" that Mite received during transformations in a mercury lamp - in each experiment they ranged from 10 -2 to 10 -4 mg - it was still a noticeable piece of gold. Gonigshmidt and his collaborator Zintl found a relative atomic mass of 197.2 ± 0.2 for artificial gold.

Gradually, Mite removed the "secrecy" from his experiments. On September 12, 1924, a report was published from the photochemical laboratory, in which experimental data were presented for the first time and the apparatus was described in more detail. The output also became known: from 1.52 kg of mercury, previously purified by vacuum distillation, after 107 hours of continuous burning of an arc 16 cm long, at a voltage of 160 to 175 V and a current of 12.6 A, Mite received as much as 8.2 * 10 -5 g of gold, that is, eight hundredths of a milligram. The "alchemists" from Charlottenburg claimed that neither the starting material, nor the electrodes and wires that supply the current, nor the quartz of the lamp shell contained analytically detectable amounts of gold.

However, a turning point soon came. Chemists became more and more suspicious. Gold is sometimes formed, and always in minimal quantities, then it is not formed again. No proportionality is found, that is, the amount of gold does not increase with an increase in the mercury content, an increase in the potential difference, with a longer duration of the quartz lamp. Did the gold that was discovered really turn out artificially? Or was it already there before? The sources of possible systematic errors in the Miethe method were checked by several scientists from the chemical institutes of the University of Berlin, as well as from the laboratory of the Siemens electrical concern. Chemists first of all studied in detail the process of distillation of mercury and came to a surprising conclusion: even distilled, seemingly gold-free mercury always contains gold. It either appeared during the distillation process, or remained dissolved in mercury in the form of traces, so that it could not be immediately detected analytically. Only after a long standing or when spraying in an arc, which caused enrichment, did it suddenly reappear. Such an effect could well be mistaken for the formation of gold. Another circumstance emerged. The materials used, including the cables leading to the electrodes and the electrodes themselves, all contained traces of gold.

But there was still a convincing claim by atomic physicists that such a transmutation was possible from the point of view of atomic theory. As is known, the assumption was made that the mercury isotope 197 Hg absorbs one electron and turns into gold.

However, this hypothesis was refuted by Aston's report in Nature in August 1925. An isotope separator was able to unambiguously characterize the mercury isotope lines using a high-resolution mass spectrograph. As a result, it turned out that natural mercury consists of isotopes with mass numbers 198, 199, 200, 201, 202 and 204.

Consequently, the stable isotope 197 Hg does not exist at all. Therefore, it must be considered that it is theoretically impossible to obtain natural gold-197 from mercury by bombarding it with electrons, and experiments aimed at this can be considered in advance as unpromising. This was eventually understood by researchers Harkins and Kay at the University of Chicago, who set about converting mercury using ultrafast electrons. They bombarded mercury (cooled with liquid ammonia and taken as an anti-cathode in an X-ray tube) with electrons accelerated in a field of 145,000 V, that is, with a speed of 19,000 km / s.

Similar experiments were also carried out by Fritz Haber when checking Mite's experiments. Despite highly sensitive methods of analysis, Harkins and Kay found no traces of gold. Probably, they thought, even electrons with such high energy are not able to penetrate into the nucleus of the mercury atom. Or the resulting isotopes of gold are so unstable that they cannot "survive" until the end of the analysis, which lasts from 24 to 48 hours.

Thus, the idea of the mechanism of gold formation from mercury, proposed by Soddy, was greatly shaken.

In 1940, when in some laboratories of nuclear physics they began to bombard with fast neutrons obtained with the help of a cyclotron, the elements adjacent to gold - mercury and platinum. At a meeting of American physicists in Nashville in April 1941, A. Sherr and K.T. Bainbridge of Harvard University reported successful results from such experiments. They sent accelerated deuterons to a lithium target and received a stream of fast neutrons, which was used to bombard mercury nuclei. As a result of nuclear transformation, gold was obtained.

The probability of any nuclear reaction occurring is determined primarily by the so-called effective capture cross section of the atomic nucleus with respect to the corresponding bombarding particle. Therefore, Professor Dempster's collaborators, physicists Ingram, Hess and Haydn, tried to accurately determine the effective cross section for neutron capture by natural mercury isotopes. In March 1947, they were able to show that the isotopes with mass numbers 196 and 199 have the largest neutron capture cross section and therefore have the highest probability of becoming gold. As a "by-product" of their experimental research, they received ... gold. Exactly 35 micrograms, obtained from 100 mg of mercury after irradiation with slow neutrons in a nuclear reactor. This amounts to a yield of 0.035%, however, if the found amount of gold is attributed only to mercury-196, then a solid yield of 24% will be obtained, since gold-197 is formed only from the mercury isotope with a mass number of 196.

With fast neutrons often flow ( n, R) - reactions, and with slow neutrons - mainly ( n, d) - transformations. Gold, discovered by Dempster's employees, was formed as follows: 196 Hg + n= 197 Hg* + g 197 Hg* + e- = 197 Au

The unstable mercury-197 formed by the (n, r) - process turns into stable gold-197 as a result of K-capture (electron from K shells of its own atom).

From the point of view of nuclear physics, several transformations of atoms into gold are possible. The stable gold, 197Au, could be made by radioactive decay of certain isotopes of neighboring elements. The so-called nuclide map teaches us this, in which all known isotopes and possible directions of their decay are presented. So, gold-197 is formed from mercury-197, which emits beta rays, or from such mercury by K-capture. It would also be possible to obtain gold from thallium-201 if this isotope emitted alpha rays. However, this is not observed. How to get a mercury isotope with a mass number of 197, which is not found in nature? Purely theoretically, it can be obtained from thallium-197, and the latter from lead-197. Both nuclides spontaneously with the capture of an electron turn into mercury-197 and thallium-197, respectively. In practice, this would be the only, albeit only theoretical, possibility of making gold from lead. However, lead-197 is also just an artificial isotope, which must first be obtained by a nuclear reaction. It won't work with natural lead.

With the same success, one could obtain the required platinum isotope from 194 Pt by ( n, d) - conversion either from 200 Hg by ( n, b) - process. In this case, of course, we must not forget that natural gold and platinum consist of a mixture of isotopes, so that in each case it is necessary to take into account competing reactions. Pure gold will eventually have to be isolated from a mixture of various nuclides and unreacted isotopes. This process will be costly. The conversion of platinum into gold will generally have to be abandoned for economic reasons: as you know, platinum is more expensive than gold.

Another option for the synthesis of gold is the direct nuclear transformation of natural isotopes, for example, according to the following equations: 200 Hg + R= 197 Au + 4 He 199 Hg + 2 D = 197 Au + 4 He.

If natural mercury is subjected to the action of a neutron flux in a reactor, then, in addition to stable gold, mainly radioactive is formed. This radioactive gold (with mass numbers 198, 199 and 200) has a very short lifespan and within a few days turns back into the original substances with the emission of beta radiation: 198 Hg + n= 198 Au* + p 198 Au = 198 Hg + e- (2.7 days). It is by no means possible to exclude the reverse transformation of radioactive gold into mercury: the laws of nature cannot be circumvented.

In the age of the atom, you can make gold. However, the process is too expensive. Gold obtained artificially in a reactor is priceless. And if we are talking about a mixture of radioactive isotopes 198 Au and 199 Au, then in a few days only a puddle of mercury will remain from the gold ingot.