Rumford, Soddy, and The Crash

Frederick Soddy (1877-1956)

Despite years of formal education in chemistry, I'd never really heard of Frederick Soddy until I started reading about the early days of radioactivity. He wrote a book called The Interpretation Of Radium (1909) which is available free online here.  The book so influenced H.G. Wells that he dedicated his book, The World Set Free (1914), to Soddy.

Soddy seems to have had two careers--first as an accomplished physical scientist (Chemistry Nobel in 1921) and then as a sort of social scientist, but more accurately as a social activist during the Great Depression. In this way he was a prototype Linus Pauling, who won both a Chemistry Nobel and a Peace Nobel for his activism.

Soddy was a chemist by training but today he'd be called a radiochemist. He must have seen or heard firsthand many of the key discoveries in nuclear physics in the late 19th and early 20th century, first at Oxford and then as graduate student with Lord Rayleigh. Afterwards, Soddy moved to Canada around the same time Ernest Rutherford did and the two joined forces. Together they discovered the natural transmutation of elements. Soddy's Nobel Prize citation reads:

for his contributions to our knowledge of the chemistry of radioactive substances and his investigations into the origin and nature of isotopes.

His isotope work came later.

Recall that Count Rumford first paid attention to the heat given off boring cannon and thereby converted our notions of energy.  Like Rumford, Soddy first realized how much heat and energy radioactive decay gave off--orders of magnitude more energy than burning fossil fuels did and it was also seemingly inexhaustible. Soddy was so prescient regarding how much energy was locked inside uranium, radium, and thorium that he warned Britain's government about the dangers of "atomic" bombs during the First World War.

The notion of cheap and abundant atomic energy crested in 1954 with Lewis Strauss' famous too cheap to meter statement, though it appears that he was referring to hypothetical hydrogen fusion reactors.

Soddy died in 1956 in relative obscurity. This (from the Wiki bio) is intriguing:

In four books written from 1921 to 1934, Soddy carried on a 'quixotic campaign for a radical restructuring of global monetary relationships', offering a perspective on economics rooted in physics—the laws of thermodynamics, in particular—and was 'roundly dismissed as a crank'. While most of his proposals - 'to abandon the gold standard, let international exchange rates float, use federal surpluses and deficits as macroeconomic policy tools that could counter cyclical trends, and establish bureaus of economic statistics (including a consumer price index) in order to facilitate this effort' - are now conventional practice, his critique of fractional-reserve banking still 'remains outside the bounds of conventional wisdom'. Soddy wrote that financial debts grew exponentially at compound interest but the real economy was based on exhaustible stocks of fossil fuels. Energy obtained from the fossil fuels could not be used again. This criticism of economic growth is echoed by his intellectual heirs in the now emergent field of ecological economics.

Ouroboros For Our Times

Frederick Soddy was fascinated with circles but also with alchemy; he related circles to his discovery of the natural transmutation of elements. Link

Through alchemy, Soddy became familiar with Οὐροβόρος ouroboros, the mythological symbol of the serpent eating its own tail. Ouroboros was also August Kekulé's inspiration for the structure of benzene, a generation before Soddy:

I may have been thinking similar thoughts when I tried to describe the circularity of political extremes and the chemical elements here. Whatever. Consider the following sketch an explicit update--ouroboros for our times--showing the demographic bulge of wealth and talent that must somehow transfer to the next generation (I should make it into an animated flip book).

Ouroboros For Our Times (click to enlarge)
Ball Point Pen on 8 1/2" x 11" white copier paper

The Kiss Precise

The Kiss Precise by Frederick Soddy

For pairs of lips to kiss maybe
Involves no trigonometry.
'Tis not so when four circles kiss
Each one the other three.
To bring this off the four must be
As three in one or one in three.
If one in three, beyond a doubt
Each gets three kisses from without.
If three in one, then is that one
Thrice kissed internally.

Four circles to the kissing come.
The smaller are the benter.
The bend is just the inverse of
The distance from the center.
Though their intrigue left Euclid dumb
There's now no need for rule of thumb.
Since zero bend's a dead straight line
And concave bends have minus sign,
The sum of the squares of all four bends
Is half the square of their sum.

To spy out spherical affairs
An oscular surveyor
Might find the task laborious,
The sphere is much the gayer,
And now besides the pair of pairs
A fifth sphere in the kissing shares.
Yet, signs and zero as before,
For each to kiss the other four
The square of the sum of all five bends
Is thrice the sum of their squares.

Published in Nature, June 20, 1936

The Frightening News First Heard In German...

Lise Meitner with Otto Hahn. Leitner, who was born Jewish, had fled Berlin that July 1938. She first spread the news of fission to the rest of the physics community.

Splitting the atom in 1938 was something wholly different than what had gone on with radiation since its discovery in 1896. To my mind, the news must have been like expanding the notion of arithmetic from simple addition and subtraction to suddenly include the concept of division. It really blew people's minds at the time. Soddy had explained how elements incrementally transmuted downwards in atomic number (subtraction) by shedding alpha particles and how they transmuted upwards (addition) in number by losing beta particles, but nobody was looking for this:*

original

In 1938, Otto Hahn and Fritz Straßmann bombarded uranium with neutrons and fished out the products. Neutrons were all the rage after their discovery in 1932 and physicists wanted to know what they did to all types of matter. Enrico Fermi had started this sort of work in Italy, but had been interrupted. It was only a matter of time before someone figured out what was going on. Hahn and Straßmann had expected to observe slightly lighter atoms like radium, actinium, and thorium; instead they observed the much lighter elements barium, lanthanum, and cerium:

Als Chemiker müssen wir aus den kurz dargelegten Versuchen das obengebrachte Schema eigentlich umbenennen und statt Ra, Ac, Th die Symbole Ba, La und Ce einsetzen. Als der Physik in gewisser Weise nahestehende Kernchemiker können wir uns zu diesem, allen bisherigen Erfahrungen der Kernphysik widersprechenden Sprung noch nicht entschließen. Es könnte doch noch vielleicht eine Reihe seltsamer Zufälle unsere Ergebnisse vorgetäuscht haben.

As chemists, we must rename [our] scheme and insert the symbols Ba, La, Ce in place of Ra, Ac, Th. As nuclear chemists closely associated with physics, we cannot yet convince ourselves to make this leap, which contradicts all previous experience in nuclear physics. A series of strange coincidences could still prove our results false.

This was the first published account of nuclear fission. Smart people realized that the exact chemical products required that more neutrons were coming out than were going in--this was soon verified and led physicists to realize that Leo Szilárd's chain reaction was now feasable. The news spread like fallout. And because it came from 1938 Berlin, the entire rest of the physics community panicked...and then they organized.**

Read more about the discovery of fission here.

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*A German chemist, Ida Noddack, had suggested as early as 1934 that "it is conceivable that the nucleus breaks up into several large fragments, which would of course be isotopes of known elements but would not be neighbors of the irradiated element"---but no one took her seriously.  link

**Another frightening fact was that the Austrians had cut off everyone else's supply of uranium from the original Czech mine--the same place Marie Curie had obtained her original samples in 1896.

"Don't call it transmutation. They'll have our heads off as alchemists"

The transmutation of elements was an ancient, discredited notion promulgated by alchemy (alchemy is to chemistry what astrology is to astronomy). Alchemists sought to turn base metals like lead into gold. They failed or were quacks and charlatans. And yet transmutation has always occurred naturally and has been practiced since 1917.

Natural transmutation was first discovered when Frederick Soddy, along with Ernest Rutherford, proved that radioactive thorium converted to radium in 1901. At the moment of realization, Soddy later recalled shouting out: "Rutherford, this is transmutation!" Rutherford snapped back, "For Christ's sake, Soddy, don't call it transmutation. They'll have our heads off as alchemists."

Transmutation became a fait accompli. But it was one thing to discover that atoms could naturally and spontaneously lose little pieces like an alpha particle or a beta particle or even a gamma ray. It was quite another thing to discover that atoms could add little pieces too.

In 1917, Rutherford projected alpha particles from radium decay through air and discovered a new type of radiation which proved to be hydrogen nuclei (Rutherford named these particles protons). Further experiments showed the protons were coming from the nitrogen component of air, and he deduced that the reaction was a transmutation of nitrogen into oxygen:

¹⁴N + α → ¹⁷O + proton

This was also the first demonstrative proof of artificial transmutation and the proton's existence.  All that was needed now was the neutron which led to division and multiplication.

"Rutherford was an artist. All his experiments had style."

Ernest Rutherford (1871-1937)

Ernest Rutherford reminds me of Michael Faraday. Born in humble circumstances in faraway New Zealand, he travelled to the mother country to study physics. Like Faraday, equal opportunity earned him a place with the best of his day and this meant the Cavendish Laboratory at the University of Cambridge. Rutherford must have witnessed J.J. Thomson's discovery of the electron there in 1897 but there's no record of him taking part in that work. It didn't matter--he had enough in him for two careers in science and a Nobel Prize of his own. And one of Rutherford's great achievements was the accidental undoing of his mentor's plum-pudding model of the atom.

Rutherford's first independent work was the unravelling of radioactivity along with Fredrick Soddy.  More on this later. But first, I want to close a loop I opened a few posts ago by hinting that I had found an inconsistency. I was referring to Richard Rhodes' account of Rutherford receiving the 1908 Nobel Prize in Chemistry:

An eyewitness to the ceremonies said Rutherford looked ridiculously young--he was thirty-seven--and made the speech of the evening. He announced his recent confirmation, only briefly reported the month before, that the alpha particle was in fact helium. The confirming experiment was typically elegant. Rutherford had a glassblower make him a tube with extremely thin walls. He evacuated the glass tube and filled it with radon gas, a fertile source  of alpha particles. The tube was gas tight, but its thin walls allowed alpha particles to escape. Rutherford surrounded the radon tube with another gas tube, pumped out the air between the two tubes and sealed off the space. 'After some days,' he told his Stockholm audience triumphantly, 'a bright spectrum of helium was observed in the outer vessel.' Rutherford's experiments still stun with their simplicity. 'In this Rutherford was an artist,' says a former student. 'All his experiments had style.' 

~Richard Rhodes in "The Making Of The Atomic Bomb"

Rhodes' book is a favorite of mine and I've read it a couple times. But Rhodes makes no mention of Soddy and Ramsey's proof five years earlier that the alpha particle was helium. According to Wikipedia:

In 1903, with Sir William Ramsay at University College London, Soddy verified that the decay of radium produced alpha particles composed of positively charged nuclei of helium. In the experiment a sample of radium was enclosed in a thin walled glass envelope sited within an evacuated glass bulb. Alpha particles could pass through the thin glass wall but were contained within the surrounding glass envelope. After leaving the experiment running for a long period of time a spectral analysis of the contents of the former evacuated space revealed the presence of helium. This element had recently been discovered in the solar spectrum by Bunsen and Kirchoff.* link

This account essentially parallels the elegant (but later) experiment announced in 1908 by Rutherford and described by Rhodes with the exception of radium instead of radon as the source of alpha particles. However, my review of the 1903 Ramsey & Soddy paper cited by the Wiki actually describes a much different and less elegant experiment. link
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*Also, Bunsen and Kirchoff didn't find helium in the solar spectrum--Lockyer did: link

A Few Words About Neutrons And Isotopes*

I learned this today from Wiki:

The term isotope was coined in 1913 by Margaret Todd, a Scottish doctor, during a conversation with Frederick Soddy. Soddy, a chemist at Glasgow University, explained that it appeared from his investigations as if several elements occupied each position in the periodic table. Todd suggested the Greek term meaning "at the same place" as a suitable name. Soddy adopted the term and went on to win the Nobel Prize for Chemistry in 1921 for his work on radioactive substances.

The concept of isotopes confounded the builders of the Periodic Table in Soddy's time. Things got even worse after J. J. Thompson showed that he could resolve purified neon into neon of two different masses, Ne-20 and Ne-22. It took the birth of quantum mechanics and Chadwick's neutron to put things back together again.

Today we know with confidence that different isotopes of the same element differ in number of neutrons within their atomic nuclei. Neutrons add heft and stability (or instability) to atomic nuclei, without changing the "place" of the element at the table; in other words, what fixes an element's place is the number of protons in its nucleus, not the sum of its protons and neutrons. Thus the concept "at the same place" makes perfect sense for different atomic mass versions of the same element. All naturally occurring elements have isotopes, for example, hydrogen, which has three isotopes so important that they're given quasi-chemical symbols of their own: H, D, and T, corresponding to protium, deuterium, and tritium, having 0, 1, and 2 neutrons respectively.

Our government (and others) have long been in the business of separating isotopes: uranium-235 was the fission fuel for the first atomic bomb, and plutonium-239 was the fission fuel for the second one. The first hydrogen bomb (code-named Ivy Mike) used liquefied deuterium-tritium gas as fusion fuel, i.e., hydrogen molecules consisting of the two heavier isotopes of hydrogen. Ivy Mike weighed around 62 tons, the bulk of which was dedicated to cooling the liquefied fusion fuel. Practical weaponization of the H-bomb was not achieved until lithium deuteride (which doesn't require cryogenics) became the fusion fuel of choice.

Iran is actively pursuing uranium isotope enrichment, ostensibly to collect enough U-235 for either peaceful electrical power generation or for a fission weapon. Less talked about is the concomitant accumulation of so-called depleted uranium (DU) which is the non-radioactive U-238 “waste” obtained during enrichment. DU is both an effective tank armor and a lethal component of bullets or rounds. While travelling at high velocity, DU or DU-coated shells burn into uranium oxide, literally forming a burning projectile. DU weapons and armor were fielded with spectacular results by the US in the First Gulf War: Iraqi tank shells literally bounced off the Abrams tanks equipped with DU armor. You can bet the Iranians were watching that with keen interest.

Isotopes also have many, many peaceful uses: think of radiochemical uses in medicine and biology and their use in determining the geologic age of materials (radiocarbon dating). Stable isotopes like deuterium and carbon-13 also find broad use as detectable labels which can also be introduced into controlled experiments and followed where they go and don't go. Moreover, subtle effects on the rates (speed) of chemical reactions gives insight into how the reactions proceed.

I once worked around neutrons as part of a scientific collaboration. Our endeavors were peaceful, despite occurring in part at Los Alamos National Laboratory. While determining the molecular structure of a certain substance, we needed the help of neutrons to locate hydrogen atoms using a technique called neutron diffraction which uses beams of free neutrons. To make a long story short, we solved the structure, but I went on to show how one could get the same essential information using more conventional instruments, but that’s another story. And that's the closest I ever want to get to loose neutrons.

*My creds include working with neutrons and co-writing a book chapter on isotopes in chemistry.