BACK TO ARISTOTLE? 1. ON URANOCHEMISTRY

B. Lukács

CRIP RMKI, H-1525 Bp. 114. Pf. 49., Budapest, Hungary

lukacs@rmki.kfki.hu

0. FOREWORD TO THE SERIES

Aristotle of Stageira is the Prügelknabe of History of Science since the French Enlightment, c. 1750. As you know, the Prügelknabe is cca. scapegoat; but in a more direct way. Originally the Prügelknabe was a substitute boy beaten if the young son of the Fürst gave a wrong answer to the tutor.

For 250 years Aristotle is beaten instead of (or: together with) the Catholic Church by Historians of Science (h. of sc.). Any ancient Greek scientist other that Aristotle may have told anything: historians of science are still enthusiastic telling that it was originally a congenial idea. Platon may have discussed the Soul which grows wings in ten thousand years and then flees above the sky; h. of sc. tell what a nice allegory. His nephew Speusippus may have written a morally terrible letter to Philip of Macedon; h. of sc. do not discuss this letter telling that it may not be genuine. Speusippus' son, Eurymedon, may have accused Aristotle for asebeia (roughly: a mortal sin against religion), h. of sc. elegantly ignore the event. Only Aristotle has no right to err.

No doubt, this aversion originated from the close ties between Aristotle and the Catholic Church. Since St. Thomas Aquinas, the teachings of the Philosopher were in the fundaments of Church Science. For some centuries almost anything which he had taught was regarded as Truth.

There are old stories, e.g. when a faculty colleague of Albertus Magnus was confronted with a fly. He was told to count the legs. His answer was: if the Philosopher's text were not clear, I should accept that a fly has six legs. (The story is too nice. The Philosopher's texts are not unequivocal about the numbers of legs of the fly. Some years ago my colleague and Aristotle expert, K. Martinás tried with a hypothesis that Aristotle counted the spider's legs and applied the result on the fly by analogy. It is possible: a fly is not only smaller than a spider, but also its legs move much faster. So it is easier to perform the counting on a spider. Remember that the number of human chromosomes was also miscounted up to the 1950's as 24 pairs, which is the correct number for our closest living relatives but not for us.)

St. Thomas Aquinas listed a very few points where he (and so later the Church) did not agree with Aristotle; they were mainly in connection with Man's Immortal Soul. Well, he could not use the gifts of Divine Revelation (albeit Sir Thomas Browne cites an antique author of Jewish religion in Alexandria who claimed Aristotle to have converted). Anyway, Aristotle is an authority in Science for the Church, and continuously ascends in authority. The (posthumous) heresy trial of Wyclif ends in 1415 with the sentence that Wyclif was indeed a heretic; some 260 points of his heresy/errors are condemned and one of them is that he contradicted Aristotle's De lineis insecabilibus. And Pierre Chaunu [1] tells us that Giordano Bruno was burned because he had refused Aristotle's Cosmology. (Indeed, the multiplicity of Suns and Earths is blatantly contrary to Aristotle.)

So, when Enlightened Catholic French freethinkers and anti-Roman Protestants find the Roman Church as common adversary, they attack Aristotle as a symbolic figure. Platon is harmless; he was simply a pagan.

Now, surely our present science is better than the Philosopher's 2350 years ago. Also, the paradigm of the recent physics is different from the Aristotelian one, except in Thermodynamics. (For other sciences, and for social disciplines the differences in paradigms are not so clear.) However, we are just learning that Nature can be described in more than one way. And paradigms cannot be disproven in another paradigm.

Galileo believed he could prove the Copernican system Now we know this would have been an impossible task. In General Relativity you may choose any coordinate system whose origo you consider at rest. In the Ptolemaic ~ Aristotelian description this is the center of Earth, and the (x,y,z) axes are fixed within Earth. With this choice some "inertial forces" appear in the laboratory; the most spectacular continuously changes the plane of the Laplace pendulum ("so proving Earth's rotation", but this is not a proof in the sense of Mathematical Logic). On the other hand, in the Copernican description the center of Sun is the origin. Then the inertial forces in the terrestrial laboratory are much more moderate; however not zero. Two old examples are the tides, well known from the time of Alexander the Great, and the aberration of starlight, observed first by Bradley in XVIIth century.

If you want to use astronomy and physics simultaneously, then you can do it for first approximation more easily in the Copernican paradigm. Without physics if you want to describe the motions of planets, it is simpler in a heliocentric coordinate system, while for the lunar motion a geocentric system is more convenient. But neither of them is "exact, so the true one".

But then, sometimes the Aristotelian paradigm may be useful even in 2007 AD. My colleague, K. Martinás succintly called my attention to this fact some twenty years ago.

ABSTRACT

Uranochemistry does not exist in post-Aristotelian paradigms (e.g. in Galilean-Newtonian one) because Heaven does not exist there. Also, Aristotle did not work out uranochemistry because he believed no changes in Heaven. Now I define uranochemistry as the most convenient chemistry of meteorites & comets. Uranochemistry obviously belongs to an Aristotelian viewpoint (Earth vs. Heaven); you may decide if it is useful or not.

1. INTRODUCTION

We now think that, as a result of 4 centuries of evolution, our chemistry is quite good, and this is of course true. However, the evolutionary path was not the only possible one; and the specific evolution resulted in a chemistry, which is still “too aqueous”. This is not a criticism; I do not claim that we would be better off in alternative schemes, and definitely the massively aqueous chemistry of Lavoisier and Arrhenius was a practical scheme to answer very practical questions. I only tell that different evolutionary paths were possible too which might have been more practical to answer other sets of questions (say: extraterrestrial ones).

The great anti-Aristotelian fervour starting in the time of Galileo & Newton has made any scheme in any science impossible or at least very heavily unfavoured in which the particular science would have location-dependent variants. Good: Newton has shown that the Physics of Up and Down can be formulated in a common scheme (in a simpler way: that the same Gravitation makes the stone fall and Luna revolve around us); but we did not have to make One and Indivisible Chemistry.

What follows here will demonstrate the possibility of an alternative way, whose idea comes from the “solvent-system” way of defining acids & bases; only observe that there are huge regions of World where there are even no solvents at all. I do not recommend the scheme of this study at all; but maybe it is useful to look at situations from alternative perspectives too.

Aristotle was a genius, 2350 years ago. We have corrected almost all answers of his. But this in itself is not a proof that his schemes would have been inherently wrong; and definitely the corrections did not prove that he would have been stupid. I would be curious how many of our nice answers will remain valid after 2 more millennia.

2. ACIDS, BASES AND NEUTRAL SOLVENTS

Acids and bases are very important in post-alchemic chemistry, but acidity and basicity are not absolute properties and even the definitions vary. For acids & bases several different definitions exist which agree only in that in aqueous chemistry hydrochloric or acetic acids are indeed acids, while sodium hydroxide is a basis.

The story starts with Lavoisier, at the end of XVIIIth century. This was the century finally substituting the Aristotelian (but rather Theophrastean) alchemy with the modern chemistry. Lavoisier found that lots of oxidised substances form acids with water, for which sulphuric acid is an obvious example. You burn sulphur; then you get SO₂ or SO₃, and with water they form H₂SO₃ or H₂SO₄. The term oxygen was coined from Greek (but not known by the ancients) meaning cca. “sourness-generating”.

Lavoisier was not general enough, as we can see on the example of the hydrochloric acid, HCl. This was soon recognised by Davy, and later by Liebig. They told that the hydrogen was the key: but of course not all H, but H’s which can easily be replaced by metallic atoms. Good; but why?

The answer came in 1884 from Arrhenius and Ostwald: chemicals are of course dissolved in water, H₂O. Now, a small part of H₂O is dissociated to H⁺ (or H₃O⁺) and OH^- ions, and if you solve something in water, that will produce positive and negative ions as well. Then acid is which gives H⁺ ions and basis is which gives OH^- ones. Other compounds are neither acids, nor bases; but they may be products of neutralisation, when an acid looses its H and a basis looses its OH. Then the result is water and a salt.

This is still the chemistry below university level. But Science goes forward, and 1923 was an annus mirabilis for the theory of acids & bases: Brönsted [2], Lowry [3] and Lewis [4] made new, more general definitions. The first two defined acids as giving protons (so having a loose –H), while bases accept the proton; Lewis defined backwards as bases giving electrons, and acids accepting them. Surely, the Brönsted definition is more generals than the Arrhenius one, but almost the same for water as solvent. Namely, take hydrochloric acid and sodium hydroxide basis, as reacting in water. HCl “donates” its H; NaOH accepts it, but in such a way that its –OH fuses with the “donated” –H. The result is HOH, water, and NaOH, salt.

So in water the Brönsted-Lowry definition agrees with the older Arrhenius one. And in other solvents?

Usanovich, Lux & Flood made even more general definitions, which I ignore here. However Haldane [5], and later Firsoff [6] took another way, to generalise the definitions for extraterrestrial situations. This way is called the solvent-system definition, and in a work about Uranochemistry I should better take this way.

For a few subsequent paragraphs you should forget that you are human born, raised and schooled on Earth.

Consider a situation when there are no solvents at all, e.g. chemistry without liquid phase(s). Then it is not natural to speak about acids. You may still, from the memory of liquids, call solid or gaseous HCl as hydrocloridic acid, but why? On the other hand, hydrochloride HCl of course will have all the absolute properties of the compound.

Now consider an exotic (for us) environment where on a planetary surface there is ample liquid phase, but predominantly HCl. In such an environment HCl would not look like an acid, because it would be simply the general solvent of the environment. Such planets are rather improbable, but only because of the cosmic element abundances: O is generally much more abundant than Cl [6]. The explanation comes from cosmology and nuclear physics and I would not go into the details here.

If you have a planetary surface where liquid phases are accidental, various and negligible for quantities, you can make liquid state chemistry, but still would not classify the compound according to the behaviour in one solvent. Such a situation is expected for the most planetary surfaces of the Galaxy, definitely if surface temperature & pressure are not fortunate. Of course, autochtonous life is not too probable on such planets, so aboriginal chemists are probably absent.

Now consider a planetary surface where the (p,T) range is appropriate for liquid H₂O. For cosmologic reasons nuclei were building up by starting from p, d, n and a and not decaying from U. So H is the most abundant atom and O, containing small, equal and even numbers of p and n is quite abundant too even if much less abundant that H. Fig. 1 gives the raw data for abundances; we will return to abundances later.

Fig. 1

As a direct consequence of Fig. 1, H₂O should be the most abundant compound in stellar systems, although on the particular planet it may or may not be in liquid phase. Still, if a planetary surface has a liquid abundant and dominant enough to define a general solvent, the biggest chance is that that solvent is water, i.e. liquid dihydrogenoxide, probably slightly sloppily called simply hydrogenoxide. (Observe that our sodium oxide is really not NaO but Na₂O. NaO exists as Na₂O₂, but the situation is analogous to H₂O₂, which is not hydrogen oxide, but hydrogen peroxide.)

So consider a hypothetical chemist born and schooled on a watery surface. Surely he, instead of performing difficult experiments with gases or very slow ones with solids, will start with reactions in liquid phase, so he will try to solve his reagents in the abundant hydrogenoxide, which he will call in a pre-chemical name coming up from Palaeolithe, as water.

Dihydrogenoxide easily dissociates to a positive, so electron-deficient ion -H⁺, and a negative one, with electron surplus, hydroxile, -OH^-. So while the overwhelming majority of this “water” will be in dihydrogenoxide molecules, a small part will be in hydrogen and hydroxile ions.

If our hypothetical chemist from wet watery surface puts some sodium chloride, NaCl into the “water” (surely, he will call NaCl on some archaic name as sea salt or common salt or kitchen salt or such), the strongly dipolar hydrogenoxide molecules will surround the strongly dipolar sodium chloride molecules and “solve the salt”. The exact process can be described in physics, and all good physicists of the Galaxy would describe it very similarly. However for chemists from planetary surfaces abundant in liquid hydrogenoxide the report would generally be: “I had put salt into water, and a part of it went into solution”.

Indeed, physics tells us a somewhat nontrivial prediction. If we put so much NaCl into H₂O that some NaCl “cannot dissolve” i.e. remains together as molecules, then a tiny amount of two other compounds is created too. Namely, there will be present the following neutral molecules and charged ions:

H₂O, NaCl, H⁺, OH^-, Na⁺, Cl^-, HCl, NaOH

The explanation is easy: first the 4 ions are created by dissociation, but then there is combinatoric possibility for the last two compounds to be formed. If there is too much Na and Cl, a few HCl and NaOH molecules can be detected by measuring apparatuses, not only the ions.

Well, from Neolithe upwards HCl and NaOH were surely familiar for the ancestors of our hypothetical watery chemist; of course for millennia not as pure materials but in strong impure solutions. The traditional names may be quite diverse, but surely touching or tasting them would give strong and quite unpleasant feelings; after some methodical experimentation it can be observed that the two compounds cause 2 different feelings, and the unpleasant feeling can be diminished by adding an appropriate quantity of the diametrically opposite material. After some millennia a precise chemist may call this neutralisation. But what does really happen?

Let us start from a “strong solution” of NaOH. That means H₂O (so common that our hypothetical watery chemist omits its explicit mention) and NaOH, the physicist calculates the quantum mechanics of the reactor (e.g. a ceramic pot) and there will be present 2 molecules and 4 ions:

H₂O, NaOH, H⁺, OH^-, Na⁺

OH^- will be more than H⁺, coming from two sources. Maybe this hydroxile surplus causes the unpleasant feeling. If we add H₂O, then we add equal numbers of hydrogen and hydroxile ions, so maybe the unpleasant feeling remains. Indeed it will, albeit the relative surplus is smaller and smaller, so our mouth or hand meets in fact less and less hydroxile excess, so actually the situation becomes more tolerable. With Neolithic terms we tell that the “solution is diluted” or “we washed away the agent”, or such. However surely this “dilution” is a cheap but not radical process.

Surely adding more NaOH the situation would go into the wrong direction; simple experiments confirm this.

However, adding HCl seems optimal; adding the proper quantity the unpleasantness ceases, and the solution becomes “quite neutral”. Putting our hand into the pot we do not feel practically anything; tasting the solution it is salty, but not unpleasant. The physicist, from any planet, will get that the reactor (the ceramic pot) contains

H₂O, NaCl, H⁺, OH^-, Na⁺, Cl^-, HCl, NaOH

and with equal numbers of the hydrogen and hydroxile ions. The salty taste comes from the NaCl molecules + the equal numbers of Na⁺and Cl^- ions, NaCl being the “common salt”.

OK, this is understood by any chemist born and schooled on a watery planetary surfaces: this is conform with his early experiences back to toddler age, and the traditions of his society beck to tens of millennia. But can he imagine the chemistry of another society, from a planetary surface where there is an abundant and dominant solvent, which is, however, not his familiar hydrogenoxide?

Surely, his everyday terms would mislead him. One can tell that an absolute chemistry would be needed, one can define a “surface-independent” chemistry, but for that first our chemist must turn to physics, as quantum mechanics. Now first I will very briefly discuss the probable abundant and dominant solvents, and then thumb rules come for some fundaments of a surface-independent chemistry.

Fig. 1 shows that H dominates all the other atoms; neglecting the passive He, by orders of magnitude. So probably abundant solvents would contain H. Then a “negative” atom is needed in addition: Fig.1 shows that the most abundant candidates are C, N and O. In our prescientific terms the resulting solvents are H₂O, water; NH₃, ammonia or hartshorn spirit; and CH₄, methane or marsh-gas. Methane is a poor solvent for simpler inorganic compounds, but ammonia is generally not worse than water, although ammonia is generally not so abundant as water. For liquid ammonia a somewhat lower temperature is needed.

Now come the thumb rules for chemistries with abundant and dominant but otherwise arbitrary solvent in solvent-system language. Let us look first a watery example but in nonwatery terminology.

If

the general solvent is H₂O

then an acid is a compound easily liberating a –H ion,

and

a basic is one easily giving -OH

Then the neutralisation is a process in which the positive H and the negative OH ions appear without the excess of any of them, as it was in the pure solvent, so e.g.

Much H-OH + Na-OH + H-Cl « Much H-OH + More H-OH + Na-Cl

In our semiscientific language:

Caustic soda + Hydrochloric acid « Common salt

(the neutral solvent is generally not mentioned in the semiscientific speech).

It is rather simple then to generalize this scheme. Let the general solvent be

A⁺ + B^-

Then an acid is A⁺-C^-, a basis is D⁺-B^-, a “neutral salt” is D⁺-C^-, and the other compounds do not classify into any of the 4 important categories of neutralisation.

E.g. consider a planetary surface where the dominant liquid is hartshorn, NH₃. Then for a locally born & schooled chemist,

If the solvent is NH₃, then acid is which easily gives –H⁺ ion, basis is which easily gives –NH^-₂ (amine), and a demonstrative neutralisation is:

Much H-NH₂ + Na-NH₂ + H-OH « Much H-NH₂ + More H-NH₂ + Na-OH

The reaction would be named by the ammonia chemist as

Sodic lye + Icic acid « Common/Kitchen salt

(the names will be explained later).

Interestingly enough in laboratories we use this reaction to get really pure NaOH, but with watery terminology as:

Sodium amide + Water « Caustic soda;

For more information about non-aqueous solvents see e.g. [7] and [8].

3. ABUNDANCES IN THE TERRESTRIAL CRUST

Fig. 1 shows the atomic abundances in the stellar neighbourhood of Sol, deduced mainly from stellar spectra. For details see [6]. This distribution should and may be approximately valid globally for the Solar System as well because of the common origin of Sol and the remaining part of his system; but surely not for the body of Earth. For example Earth is depleted in volatiles as H and He. Of course we do not have good sampling about the total Earth.

Again, Earth has gravitationally and thermally been differentiated, so we expect the heavy or highly melting components deep, in the neighbourhood of the center, while the cool crust is probably composed of light/easily melting components. We do not know the abundances for the crust but do know them for the upper crust, where "upper" is defined by the depth available in sampling. Selection processes for Earth and the terrestrial upper crust very much deform the primary abundances: the selection function is shown as Fig. 2. As we see, H is not the most abundant element in the upper crust (albeit not rare); O or Si are more abundant. As a good example for the selection, in the cosmic average Mg is roughly an order of magnitude more abundant than Al (they are produced in very similar nucleosynthetic processes, but Mg is an even-even nucleus while Al is not); still, in the terrestrial upper crust the relation is the opposite. This distortion of abundances is caused by (gravitational & thermodynamic) differentiation, whither we return later.

Fig. 2

4. ON OUR HEAVEN

Of course in the Solar System abundances are changing from planetary body to planetary body. As for the whole body this is the consequence of the primordial condensation process: planets farther from Sol could collect more volatiles [9]. But surfaces differ even more; the differentiation process had its pecularity for each body. So there would be a specific chemistry for each surface. Of course, there is the same physics on all the surfaces; however, if the name chemistry means more for us that simply applied physics, then the specific chemical rules change from surface to surface. For example, with the possible exception of Mars and the Iovian satellite Europa, dihydrogenoxide is not the general solvent in the Solar System outside Terra; and there is certainly no general solvent on Luna, Mercury, Venus and the asteroids. And if you cannot naturally define the general (neutral) solvent, then there is no natural definition or even meaning behind the notions of acids, bases and neutralisation (except than some terrestrial reminiscences).

In this work I call everything "planet" in the Solar System which is a center of gravity, so of accumulation, in a neighbourhood of non-negligible size. So Sol is a planet, Terra is a planet, Luna is a planet, even asteroid Vesta is a planet. A planetary surface is a place which significantly differs from the planetary body (gravitational differentiation) and whence you can look upward to Heaven (so a local center of spontaneous symmetry breaking from E(3) to SO(3) via gravitation is somewhere well inside the planetary body). Heaven is practically the non-accumulated remainder of the Solar System; negligible for mass but huge. And really it is Upwards, at least from our actual coordinate system, adapted to the local symmetry breaking.

This Heaven contains solar wind, comets, meteoroids, the smallest satellites and the smaller asteroids; we believe that there is not real difference amongst the last 3 groups: meteorites are small asteroids accidentally meeting Terra and the smallest moons of Jupiter and Saturn are just captured asteroids.

There are no planetary surfaces in this Heaven; a very small asteroid has a surface in geometric sense but otherwise not, the whole body is a homogeneous lump of matter. So there is no liquid phase at all in Heaven.

On the other hand, we have good sampling of the material composition of Heaven, thank to meteoritics and especially to the methodical work of the National Institute for Polar Research in Tokyo, Japan for decades, who collect meteorites from Antarctica and determine their composition. (For a stage of this work see [10].) We know much less about comets, but this will change in a few years.

5. ON THE ORIGIN OF METEORITICS

In the recent decades most people in meteoritics have originated as geologists or in related topics. I think this is because you use very similar technics to analise a meteorite and a terrestrial rock. Howevr geology had a quite terrestrial origin.

In the Early Modern Ages, say in XVIIth century, and especially after the Thirty Year War, Germany had a lot of small universities. The Muenster-Osnabrueck Peace in 1648 seriously reorganised the Holy Roman Empire of the German Nation. The Empire remained, there was an Emperor, there was a common Imperial Law with an Imperial High Court in Wetzlar and such. But lots of local rulers became souvereigns, in the sense that they had even the right to make wars on each other (not on the Emperor, of course). There were no Kings in the Empire except the King of Bohemia; the Prussian King was a King of Prussia outside the Empire, and it was an accident that the Austrian Archdukes were generally Kings of Hungary, Kings of Croatia, Kings of Dalmatia and Kings of Jerusalem. But there were Princes and Dukes. And some Marchgraves and Counts were also declared sovereigns. The smallest sovereign German statelet whose complete data I have been able to collect was County of Solms-Rodelheim, c. 100 square kilometers (2 Prussian sq. miles), pop. 6,000, the yearly state income (taxes, duties &c.) 30,000 florins (guldens).

Now, the simplest important outward signal of suvereignity was of course the army. Prince Louis Frederick Charles of Hohenloche-Oehringen (360 sq. km, 25,000 pop.) had a few hussars, a hundred infantry, with officers, a drummer and a trumpeter. However there definitely were smaller armies. Dukedom Isenberg-Büdingen (12,000 pop., 60,000 fl. income) had 20 soldiers, and County Limpurg-Styrum in a time had an army of 1 colonel, 6 other officers and 2 privates. Of course, this army was purely ceremonial, a mere declaration; but this is just my point. (And observe that San Marino, 61 sq. km, pop. 17,000, had 180 soldiers in 1964; state income 3.5 billion liras ~ 100,000 fl.)

Declarations of independence were important because there were continuously some changes in the Empire. Sometimes sovereign families died out, sometimes the Emperor split a state between two sons (in Saxony this went into extremes) or sometimes a non-sovereing count applied his Prince or the Emperor for upgrading. For this some item of prestige was useful.

An item of prestige was a University. It was not so cheap or simple as an army, so the smallest states did not have their own universities; but there were many universities in Germany. (In the same time there were only two universities in England.) But university staff was not overawed. Pince Frederick William of Mecklenburg (pop. 100,000) classified the state employees into 24 degrees of rank in his Hofordnung für die Civil-, Militär- und andere Bediente. The first rank was one single subject: the president of the Privy Council. The 24th rank was the coachmen and wood carriers (in state employ). Now, the highest rank for university staff was Rank 11: all faculty professors except Philosophy. For comparisons, Rank 10 was the Mayor of Rostock, and Rank 12 included the Captains of the Army.

A University is useful in many ways. E.g. to the birthday of the Ruler the university staff can write or read poems. But of course the Ruler disciplined the staff if needed. For example Charles Theodore, Elector-Prince of the Palatinate issued a decree on Feb. 1, 1785, stating that Prof. Weishaupt of the Faculty of Philosophy ordered too many books of Bayle. The case must be examined. Some days later the Ruler ordered that: Prof. Weishaupt declare his Catholic faith; instead of Bayle's Dictionaire historique et critique the library buy the two-volume book of Zabuesnig; the Faculty of Philosophy cease to exist. Karl Zeller’s operetta Der Vogeler (The Fowler) gives a caricature of the (Austrian) opinion about professors of universities of smaller German states when the protagonist Adam the Fowler is examined for court position with the support of the wife of the local ruler.

While Geology is a honourable Science, geology, as evolved in Early Modern Ages was somewhat influenced by the statuses of German universities. New results are needed; but results not only new but also demonstrative. A new kind of rock is good (a substantial part of Germany was a mining area), but a new kind of rock which is purple with emerald green spots is even better; then the Ruler, when visiting the University, will see how hardly the university works and maybe even his Wife will remember the nice rock. The new mineral will be immediately named; boring minerals will get the names of the discoverers, but if something is purple with green spots, it will get at least the name of the Countess.

Therefore emerging Geology concentrated on Variety; it described thousands of minerals with individual names.

Now, this great variety goes back to terrestrial differentiation. Meteorites do not come from Terra, and the majority never belonged to any planetary bodies. We can recognise those which were formed originally in Mars, Luna and Vesta, the iron meteorites had been formed as cores of big asteroids, demolished later, but almost all the others, and certainly all chondritic meteorites, have been formed in Heaven.

In Heaven there is no General Solvent. So it is no point to define Acids & Bases (the definition would be not only arbitrary, but pointless as well). Then there is no Neutralisation either; and no liquid phase reactions. The Colourful Geology of the above paragraphs could exist only on some major planets (Terra, Mars, Luna, Venus; we do not see the surfaces of the giant planets); even big asteroid Vesta (whose crust we know quite well from diogenite, howardite and eucrite meteorites) could not have fed the universities of Germany in XVIIIth century even for a couple of decades. So Chemistry of Heaven (uranochemistry) would not contain lots of complications present on the surface of Terra, so could concentrate on other points. However first let us finish with the planets, in order to see clearly what is the chemical difference between Terra and Heaven and how we can be sure which meteorite is of planetary origin and which is the product of Heaven.

6. PLANETARY DIFFERENTIATIONS

There are good signals showing that Sol, other planets and matter in Heaven have mainly common origin, a galactic cloud starting to contract c. 4.55 billion years ago. External contamination is probable but seems not too extensive.

The bigger asteroids (surely upwards c. 100 km radius, maybe the borderline is somewhat below) are spherical. So at the beginning even they were molten. While we still are not certain, why and how, medium life time radioisotopes as Al²⁶ or Pu²⁴⁴ may be behind. In liquid state gravitational differentation is easy. So we can visualize the evolutions of all rocky planets in, say, 6 consecutive stages, as:

Stage 1: Everything is molten. There is some gravitational differentiation (see Fig. 3 below), but convection counteracts differentiation.

Stage 2: Cooling has formed a thin solid crust; however the liquid below can regularly break it. In terrestrial language we can speak about extensive lava flows; but this lava is not too differentiated, it is near to the bulk distribution of the planet. (But metallic Fe is accumulating in the center.) This stage is preserved in the diogenites of/from Vesta, and maybe the lherzolites and oldest komatiites of Terra.

Stage 3: The crust has become thicker, and the undifferentiated Mg>Al lava has difficulties to come up (gravity tries to keep heavier Mg-silicates below, being they of high melting point, some of them freezes midway, &c.). So Al>Mg lava starts to cover the Mg>Al surface. On Terra the really old basalts are rather komaiitic, the newer ones rather not.

Stage 4: The crust has become more thicker. Generally volcanism is in separate spots, through long shafts. The matter reaching the surface is generally light and of low melting point; both conditions prefer (Al,Ca) and even more Na to (Mg,Fe). See: eucrite (Vesta), basalts (Venus, Terra, Luna, Mars).

Stage 5: Some up to now unknown mechanism disprefers Al to Ca on Luna and Mars. On Terra there is an opposite preference, but this may be biologic. See Fig. 4 for extraterrestrial basalts and Fig. 5 which include terrestrials as well.

Stage 6: Volcanism stops. For some time there is still post-volcanic activity of gases but this does not leave permanent traces. Maybe Mars is now in post-volcanic stage; and on Terra we know local examples, e.g. Hargita is the only mountain still showing post-volcanism in the whole Carpathian Basin.

When volcanism stops, the surface cannot anymore be rejuvenated. Composition freezes or slowly corrodes, depending on the atmosphere.

Fig. 3: Al vs. Mg abundances for chondritic and Vestan basaltic meteorites. Diogenites are still near to the primordial composition.

Fig. 4: Ca vs. Al contents for Vestan (Dio, Eucgen, Eucpol, How), Lunar (Lun) and Martian (She) basaltic meteorites + some others whose origin is still unclear. Observe that Lunar and Martian basalts prefer Ca; for the others the Ca/Al ratio is cca. the chondritic one which in turn is near to the cosmic abundance ratio.

Fig. 5: Ca vs. Al contents for Terran and Vestan basalts. Observe that older Terran basalts (komatiites) deviate upwards from the cosmic abundance ratio, while younger ones deviate downwards.

The undifferentiated matter seems to be preserved in chondritic meteorites. Fig. 3, at least for Al and Mg, show that they have abundances similar to the cosmic one, and in fact for all elements going easily to solid state this is more or less true. For eucrites, howardites and diogenites the textures show that the matter had been melted in the past, even if for diogenites the abundances would not disprove primordial origin. We can recognise lunar & Martian basalts and lunar anorthosites as well, having lunar rocks at hand and probes on Mars. Iron meteorites are surely remnants of cores of differentiated asteroids demolished in the past. The crusts of these demolished asteroids are certainly in the samples and experts have some guesses about them. All other meteorites are heavenly.

7. ELEMENTS IN HEAVEN

While in principle all elements of the periodic table which can be found in terrestrial natural conditions do exist in Heaven too, some of them are extremely rare, so they are not needed in first approximation to Uranochemistry. For a guess see Fig. 1; but since elements can be suppressed in entering solid phase, some corrections are needed too. We take 3 steps.

Fig. 6 is the first 4 rows of the periodic table, Si-normalised abundances as in Fig. 1, but a different display. Noble gases, not participating in chemical processes, are omitted. Fig. 7 is the same for the upper terrestrial crust, so the analogue of Fig. 2. Since there are already more than 8 columns in Row IV, each row is labelled with its most common element.

Now, Fig. 8 is the same, but for the rare metorite class C1, maybe under the minimal thermal impact in the past so most primordial, the meteorite Y-82162 from the NIPR collection. Elements beyond Row IV are rare in Heaven (see Fig. 1).

Fig. 6: Si-normalised cosmic abundances for the first 4 rows of ther periodic table.

Fig. 7: As Fig. 6, for the terrestrial upper crust.

Fig. 8: As Figs. 6 & 7, for the rather unaltered meteorite Y-82162.

Obviously in Chemistry of Heaven all elements are important which are abundant there. However, for minor components, we have another factor, standard potential. Atoms of elements can yield an electron easily (e.g. a large alkali atom its outermost electron above a "closed shell"), or not so easily (a small alkali where even the outermost electron is near to the nucleus, or an alkali earth one of the two outermost ones, leaving behind not a closed shell, or such). Or they would rather not yield an electron but would take one easily (a small halogen, which can make its outermost shell closed by taking one), or still rather take than yield, but not so easily (a large halogen, or a Column VI atom which will not have a closed shell even then, or such). Standard potential is measured in Volts, well above +1 V for alkalis and well below -1 V for halogens. It can be measured also for some molecules or radicals if they do not disintegrate in the measurement.

Now, Fig. 9 shows the periodic system down again to Row 4. If an element is rather rare and fairly inert, then it can be overlooked in Uranochemistry and still the description is good. Question marks appear for various reasons. Sometimes I did not find the data. Sometimes the element simply does not produce ions in aqueous solution; and the standard, or electrode, or redox, potential was a par excellence aqueous quantity until recently. (Now some data are available in liquid ammonia solvent, and they do differ from those in water.) And carbon is the best example for uncertainty: while it has no ions in aqueous solution, so the redox potential cannot be directly measured, the solid state structure seriously influences the redox behaviour of carbon. Amorphous carbon reacts quite aggressively with oxygen, as we see it from the fact that it can take away the oxygen from FeO. Diamond and graphite burn also vehemently. But buckminsterfullerene, C₆₀, is an electron acceptor, so “negative”, although it is also pure carbon. So the electrode potential does not yield a final understanding of chemistry in Heaven; still it gives some insight.

True, the values have been measured at 1 atm, and 25 centigrades, but in first approximation they are determined by electron shell structure, so the changes from lab to Heaven environment are probably minor.

Fig. 9: Normal potentials for the first 4 rows of the periodic table.

Now let us combine Figs. 8 & 9 (or Fig. 8 could be replaced by one for all chondrites; no big difference). I go from column to column; boldfaces stand for elements of first order importance in uranochemistry.

Column 1, alkalis. 3 elements occur with non-negligible abundances, but K is much rarer than Na and the latter rather mimics K. So Uranochemistry can work with two alkalis, a strong one, Na, and a weaker one, H. Fig. 10, below, will demonstrate the Na-H competition in chondrites, but first we should finish the listing.

Column 2, alkali earths. Be is of negligible abundance. We remain with Mg and Ca.

Rare earths. They are negligible.

Columns of Ti, V, Cr, Mn: Their abundances are rather negligible.

The columns of the iron triad: Only Fe is really abundant; Ni generally occurs together with metallic Fe, and Co is rare anyway, so we remain with Fe.

Columns of Cu and Mn: Their abundances are rather negligible.

Column 3: Only Al is abundant not to be ignored.

Column 4: Two elements have non-negligible abundances, C and Si. Their roles are quite different (see later).

Column 5, of nitrogen. Interestingly enough, N is negligible in the heavenly solid phases; I do not quite understand, why, but this is an observational fact (causing difficulties to understand the Beginning of Life on Terra, but that is another matter). P may or may not be omitted.

Column 6, of oxygen: Both O and S are important and abundant.

Column 7, halogens: All are of negligible abundances. However I believe that for Cl this is an artefact of terrestrial wet environment + aqueous analytic methods, so I would suggest to keep it.

This is a scheme with 9 elements, rather similar for complexity to medieval alchemy of 5-10 elements. Similarly to that, the 9 elements may represent also a few more (e.g. Fe represents also Ni), but unsimilarly, we can be sure that the neglection of the remaining 83 cannot really influence the final results.

On another, more Aristotelian, language we may call them as:

The weak alkali (H).

The strong alkali (Na).

The heavy earth (Mg).

The light earth (Ca).

The Jolly Joker (Fe).

The Valence 3 earth (Al).

The volatile (C).

The Rock Maker (Si).

The agressive non-metal (O).

The non-agressive non-metal (S).

The halogene (Cl).

Fe is the Jolly Joker because it may appear both in the metallic phase and in the non-metallic one, with both valences 2 and 3, and both with O and with S. C is the volatile, because its abundance changes very much with previous thermal history. Fig. 10 shows that Na and H substitute each other in Heaven; maybe the actual anticorrelation was caused by the competitions of the 3 alkali oxides Na₂O, NaHO and H₂O at primordial condensation. As for Rock Maker Si, a new Chapter is appropriate.

Fig. 10: Na-H competition for C2 and C3 meteorites.

8. ON PROCESSES IN HEAVEN

In all stone known meteorite the texture is determined by an SiO₂ lattice. In older or more conservative geology/chemistry books you can read that the silicates are salts of the silicic acid, H₂SiO₃. Indeed, in terrestrial chemistry, with H₂O as general solvent, there are reactions suggesting such a view. They go mainly backward, but even then...

If you heat up meta silicic acid H₂SiO₃, it slowly yields water, and amorphous quartz remains, as

H₂SiO₃ → H₂O + SiO₂

So in aqueous chemistry quartz sand seems to be the anhydride of silicic acid. The statement is almost meaningless, however, because it is almost impossible to solve quartz sand in water.

Still, insolubility is formally not a counterargument. See e.g. aluminiumoxide, Al₂O₃. It is insoluble in water, however a formal reaction Al₂O₃ + H₂O would (if could) give aluminiumhydroxide Al(OH)₃. It is still hardly soluble in water, but reacts with acids in a regular neutralisation.

Now, the sodium silicate, which is fairly soluble in water, has formally some relation to a silicic acid as it can be seen from an inverse reaction:

Na₂SiO₃ + H₂O + 2HCl → 2NaCl + H₂SiO₃ +H₂O

However surely the silicates of the terrestrial crust have not been created in an aqueous neutralisation reaction of a silicic acid and a basis as e.g.

H₂SiO₃ + Mg(OH)₂ + much water → MgSiO₃ + more water

because there was never enough H₂O in the body of Terra to solve the necessary amount of quartz sand or silicic acid, and according to Terra's reconstructed history there was no significant quantity of Mg(OH)₂ in Terra. Really, the reconstructed terrestrial history goes into a quite different direction: silicates directly condensated from the protosolar nebula. There is no known meteorite which would have ever evolved in a dominantly aqueous environment. While C1 and C2 meteorites are "wet" even in them the dihydrogenoxide is not the dominant component.

There were never solvation processes in Heaven. On the other hand, at Beginning of Times (at the Birth of the Solar System) there was condensation from hot (or, far out, tepid) protosolar gas. Of course we could tell that there is only one chemistry; but then it could not include acids & bases whose classifications do depend on the solvent; and if there was and is no solvent at all...?

Going back to SiO₂, in some strange way, SiO₂ plays a similar role in uranochemistry (but in solid phase) as H₂O does in terrestrial chemistry. Stony meteorites are dominantly silicates. Then in meteorites you can observe textures of, say, MgSiO₃ as well as of Mg₂SiO₄. However, they are not really valence compounds. Rather, the first is SiO₂*MgO, while the second is SiO₂*2MgO. The SiO₂ can build up an infinite lattice in 3 dimensions, each Si being surrounded tetrahedrally by 4 O's and so on. Now, there are free places in the lattice where Me_aO_b oxides can enter. But the inclusion of metallic oxides of course deforms the silicon lattice.

Now, SiO₂ is an analogon of H₂O in two ways. The first, more direct way is to look at SiO₂ of uranochemistry as the crystallic water of aqueous chemistry. The second way is to tell that in some sense meteoritic silica is the "neutral carrier" of metallic oxides, carbon, iron sulfide and metallic iron. Many times we can qualitatively describe the reaction even without speaking about the silica. Of course then even pyroxene is not much distinguished from olivine.

9. CLOSING REMARKS

I am not criticising usual chemistry. It does work well. Only, under extremely non-terrestrial situations it is not the simplest way. Without lots of dihydrogenoxide the statements about solubility, the acid-basis dichotomy and such are either practically meaningless, or misleading, and in both cases we should forcibly forget them.

Now, for a demonstration of the usefulness of local chemistries consider a dominantly liquid ammonia environment. I do not know if it occurs anywhere in the Solar System (if so, then outward [11]), and it definitely does not occur in Heaven, but it may occur somewhere (and there is a mysterious observation about Origin of Life, see later). Now, how to try to describe Chemistry of this Alien World?

On an ammonia-washed planet autochtones would not be disturbed about our ideas about acids, bases and salts. There the reaction of their rather simple compounds, known in impure states since Neolithic time

NaNH₂ + HOH = NaOH + NH₃

would really be read as: common lye can be neutralised with icic acid, and they get common salt/kitchen salt + moisture is liberated. Why would they read it in this way?

Well, their common solvent is NH₃=H-NH₂. Their tissues are full with NH₃. It is quite neutral for them, it does not attack their bodies, their biology is the product of billion years of evolution in NH₃. (Of course, they would not call their general solvent “ammonia”. And even in their Middle Ages they did not call it “hartshorn spirit” because it was not a specific material. Maybe “moisture”, or “sap”.) But NaNH₂, our sodium amide, is a quite common aggressive compound, a lye. Why?

The explanation goes in two parts. First, ammonia dissociates (in a small amount) to H⁺ and NH₂^-. Ammonia is neutral, having the above radicals in equal amounts. But if we add NaNH₂, the ion balance ceases. The solution will have a great excess of negative ions. So our sodium amide is there a strong caustic, sodium lye.

In addition, their sodium lye must be quite common. Namely, sodium oxide is only some 1 % in chondrites. However, sodium silicates are light and are melt at relatively low temperatures, so late volcanism brings up Na-rich basalts. This is pure physics (gravity + thermodynamics) so it is independent of the solvent on the surface. Therefore sodium must be a common enough element, and some of its compounds are solved fairly well (in ammonia, of course). Also there are reports that even metallic Na can be solved somewhat in ammonia (I guess, because of the alkalic metal-type behaviour of the NH₄ group, see ammonium amalgam), although we cannot expect too much metallic Na in natural environment. Maybe their soda lye was first produced also from natural Na₂CO₃.

Now, HOH in NH₃ environment gives the positive ion of the solvent but not the negative one. So it acts on the discussed extraterrestrials just as our acids do on us. But HOH must be an abundant compound there, because ice is an abundant component of many stellar systems (according to calculations) due to the high abundance of the elements H & O (see Fig. 1). However in their environment HOH is solid, a rather light rock. So it is a rock which is acidic if you taste it, icic acid.

Now, if soda lie is abundant and common, NaOH, spontaneously coming from fairly common soda lye and the abundant acidic rock is neutral, so can be eaten. Also, it contains the radicals Na- and -OH. I guess, for them both are necessary, but surely at least Na. Na is important for all terrestrial creatures, a useful metallic ion, so why not there? So "common salt" is a good name. If it has even some taste for them (why not?), then it may also be "kitchen salt". Anyway, it is very probable that their seas contain NaOH, because Na comes from sodium silicate and OH from the acidic light rocks found everywhere; and then Life started in the seas and for sophont land animals NaOH is matter of life and death to maintain the primordial chemistry. Originally this was doubted: Ref. [5] tells that NH₃ does not solve the alkali chlorides. But NaCl is an exception; although ammonia solves it less than water does, still a concentration similar than in seawater is possible.

This few paragraphs were the draft of an essay about ammonia-chemistry produced without lots of quantum mechanical calculations. I am certain enough to write it down; if somebody wants to check the reaction in ammonia solvent, a moderately low temperature lab is needed, with breathing masks. Without liquid phase the reaction is standard even in our laboratories.

However now comes the Mystery of Life. Terrestrial life uses amino acids as LEGO building blocks of proteins, some 20+ rather small molecules from which huge proteins can be put together.

Obviously such building blocks should be "bipolar", having two opposite characters at the two ends. Then if you make two to react with one positive and one negative end, the result will be a bigger molecule again with a positive and a negative end, and the process can be repeated.

In aquaeous chemistry the most natural choice for a bipolar reaction is neutralisation. Also, for long chains C is needed, so the thing must be done in organic chemistry, where the compounds must have a -COOH end to easily loose -H (obviously from reasons understood only via Quantum Mechanics; I never calculated this. Really, the radical would be better to write as one O with a double bound out of the plane of the paper, and the other as -O-H; and then it would be easier to imagine that -COOH yields merely an -H; but this would be a Figure, not a text.) Good, so the simplest organic compound which is acid on one side and basic on the other (so an oxyacid) is the glykolic acid:

HO-CH₂-COOH

(the trivially simple HO-COOH not working in the proper way for symmetry reasons).

You might expect that two glykolic acid molecules would react as

HO-CH₂-COOH + HO-CH₂-COOH = HO-CH₂-COO-CH₂-COOH + H₂O

but it is not so. Rather the long molecule rearranges as:

HOOC-H₂C-O-CH₂-COOH

and that double acid is a cul-de-sac.

Terrestrial life has found the way out by using amino acids instead of oxyacids, the first member of the sequence being then glycine:

H₂N-CH₂-COOH

Now, two glicines react in a proper way as

H₂N-CH₂-COOH + H₂N-CH₂-COOH = H₂N-CH₂-CONH-CH₂-COOH + H₂O

giving another molecule with an amid and a carboxyl end, so that is another LEGO. (-CONH-, which again should be a picture, is the peptide bound, characterising the proteins.)

That is really nice; but on one end of the building blocks of Life there is not the familiar hydroxile radical of aqueous chemistry, but the familiar amino radical of ammonia chemistry.

The peptide bound of aqueous organic chemistry seems to belong to ammonia chemistry! (Wait a minute.)How is this? And why is this? I do not know. But I can make an easy prediction for life in ammonia planets. There a very similar trick is expected to work, starting with proper bipolar molecules of ammonia chemistry:

H₂N-R-CONHH

If -R- is the simple -CH₂-, then the molecule exists also in our aquaeous organic chemistry, and is a building block of oxytocine. Now, put together lots of such ammoniac aminoacides. With repeated ammonia loss a chain builds up

H₂N-R₁-CONH-R₂-CONH-...CONH-R_n-1-CONH-R_n-CONHH

Now,

H₂N-R₁-CONH-R₂-CONH-...CONH-R_n-1-CONH-R_n-COOH

is the corresponding protein of aqueous chemistry, and if the molecular weight is ~10⁶, the difference in the very last radical is relatively almost nothing, so if one polypeptide is stable, the other is so as well. So Life in ammonia solvent is more natural than in aqueous one.

For summarizing: Long live Aristotle! In the last 2300 years most of his answers and explanations have been disproven; but I would like to see the physics of 4300 AD to check the fates of our answers & explanations. Some of the Philosopher's pictures were fundamentally good (see Thermodynamics) and some are still not sheer lunacy (as e.g. the distinction between Heaven and Planet in chemistry).

ACKNOWLEDGEMENT

Discussions with K. Martinás about Aristotelian and non-Aristotelian paradigms and their relative merits in natural sciences are acknowledged. The starting point came from these discussions, which were originally suggested by her.

REFERENCES

[1] P. Chaunu: La civilisation de l'Europe classique. Arthaud, Paris, 1966

[2] J. N. Brönsted: Some Remarks on the Concept of Acids and Bases. Rel. Trav. Chim. Pays-Bas 42, 718 (1923)

[3] T. M. Lowry: The Uniqueness of Hydrogen. Chem. Ind. Lond. 42, 43 (1923)

[4] G. N. Lewis: Valence and the Structure of Atoms and Molecules. The Chemical Catalog Co., New York, 1923

[5] J. B. S. Haldane: The Origins of Life. New Biology 16, 12 (1954)

[6] V. A. Firsoff: An Ammonia-Based Life. Discovery 23, 36 (1962)

[7] G. Jander & W. Klemm: Die Chemie der wasserähnlichen Lösungsmitteln. Springer, Berlin, 1949

[8] L. F.Audrieth & J. Kleinberg: Non-aqueous solutions. J. Wiley & Sons, New York, 1953

[9] Eva Novotny: Introduction to Stellar Atmospheres and Interiors. Oxford University Press, New York, 1973

[10] K. Yanai, H. Kojima & H. Haramura: Catalog of the Antarctic Meteorites. NIPR, Tokyo, 1995

[11] S. S. Barshay & J. S. Lewis: Chemistry of Solar Material. In: The Dusty Universe, eds. G. B. Field & A. G. W. Cameron, Neale Watson Acad. Publ., 1975