In a Single Spoon… the power of all the world’s radium

So terrifyingly powerful is Cobalt 60 — radio-active offspring of the atom bomb and great new weapon in the fight against cancer — that a single spoonful produces as much radiation as all the radium in the world.

And Cobalt 60 is but one of many radio-active isotopes, spawned by the Atomic Age, that offer benefits and advances in medicine, industry and agriculture. Realization of these promises depends in part on development of economical and versatile materials for shielding the ffhot” isotopes.

One such material is Mallory 1000 Metal, a high density alloy of tungsten, nickel and copper that has already proved itself a highly effective shield for ”containing” deadly radiation.

Requiring far less space than other shielding materials, Mallory 1000 also is easily machined to almost any size or shape and thus lends itself to a wide range of applications . . . storage containers for isotopes . . . reactor shields . . . oil well loggers . . . medical equipment . . . many kinds of meters and instruments.

Because of its high density and machinability, Mallory 1000 is widely used in gyroscope rotors and in counterbalances where great weight is required in small space.

It is a unique and versatile product—typical of the precision quality of all Mallory products in the fields of electronics, electrochemistry and specialized metallurgy.

Mallory SERVING INDUSTRY WITH THESE PRODUCTS:

Electromechanical • Resistors, Switches, Television Tuners, Vibrators.
Electrochemical • Capacitors, Rectifiers, Mercury Batteries.
Metallurgical • Contacts, Special Metals and Ceramics, Welding Materials.

view additional pages

WHAT IS YOUR ATOMIC IQ?

By J. Robert Connor

GREEK philosophers some 2,000 years ago are believed to be the first people to theorize that there were tiny and invisible particles in all matter. They named these particles atoms. To give you an idea of the smallness of these particles, it is said that if all the people of the world were as tiny as atoms, we would all be able to stand on the head of a pin! Since the atom seems to offer us a bright future, barring war, we should know something about it. This quiz is designed to test your atomic acumen. How do you rate?

True or False (underline one)
1. The first atomic-powered merchant ship to be built by the United States will cost an estimated $39,000,000. The name designated for this vessel by President Eisenhower is the N.S. Savannah. True. False.

2. United States scientists were the first to discover atomic energy. True. False.

3. The A-bomb derives its tremendous energy from atomic fusion. True. False.

4. A reactor is an atomic furnace. True. False.

5. Uranium, the source of nuclear fuel, is far more radioactive than radium. True. False.

6. Pitchblende is an ore containing both radium and uranium. True. False.

7. Isotopes are made up of almost identical atoms that behave chemically the same but have slight differences in their atomic weight. True. False.

8. The latest use for atomic energy, according to the Atomic Energy Commission, is the explosion of a nuclear bomb underground which is expected to open a vast new field in mining and oil techniques. True. False.

9. The inner core of the atom is called the nucleus. True. False.

10. Food irradiated by atomic particles is now being eaten by the United States Army. True. False.

Multiple Choice (underline one) 11. The name of the United States Navy’s first atomic-powered submarine is: Seawolf; Nautilus; Skipjack.

12. Master slave manipulators are: mechanical hands used to handle radioactive materials; mechanical hands used to dig up uranium ore; device used to measure atomic energy.

13. The first commercial atomic power station in the United States is located in: Shippingport, Pa.; Los Alamos, N. M.; Oak Ridge, Tenn.

14. A Geiger counter is an instrument used to: measure radioactive elements; count atomic particles; detect the presence of radioactivity.

15. The nucleus of an atom consists of: electrons and neutrons; neutrons and protons; electrons and ions.

16. A critical mass is: a radioactive pile; amount of nuclear fuel needed to sustain chain reaction; massing of protons.

17. The word “hot” means that a substance is: burning; undergoing nuclear bombardment; highly radioactive.

18. The best shield laboratory workers can use to protect themselves from radiation is: iron; steel; lead.

19. A roentgen is: a unit of radioactive dose; critical mass; radioisotope.

20. The chairman of the Atomic Energy Commission is: John A. McCone; Thomas Murphy; Lewis L. Strauss.

21. The most important material used in atomic energy operations is: U-234; U-238; U-235.

22. The man who proved by experiments that the atoms of various elements are not alike and that each has its characteristic weight was: Albert Einstein; John Dalton; Isaac Newton.

Answers
————————————-

1. True. The first steamship to cross the Atlantic was the S.S. Savannah in 1819. The first atomic-powered merchant ship will be named after it and called the N.S. (Nuclear Ship) Savannah.

2. False. German scientists discovered modern atomic energy in 1938.

3. False. Atomic fission, the splitting of heavy nuclei such as uranium, releases the energy that explodes the atomic bomb.

4. True. An atomic furnace is called a reactor and is designed to withstand the tremendous amount of energy produced by the splitting of atoms.

5. False.

6. True.

7. True.

8. True. Recently the AEC set off an atomic explosion deep in a Nevada mesa. The AEC believes that this new method will lead to obtaining minerals and oil from the ground much more easily and cheaply than is now possible.

9. True.

10. False. Research in this field has been going on for quite some time and the armed forces plan to test irradiated foods in the near future.

11. Nautilus.

12. Mechanical hands used to handle radioactive materials.

13. Shippingport, Pa.

14. A device used to detect the presence of radioactivity.

15. The inner core of the atom consists of neutrons and protons locked together.

16. The amount of nuclear fuel necessary to sustain a chain reaction.

17. Hot means highly radioactive.

18. Lead.

19. A roentgen is a unit of radioactive dose, or exposure.

20. John A. McCone.

21. U-235. Scientists have discovered that U-235, a rare isotope of uranium, is the atom that is most easily split.

22. John Dalton, a Quaker school teacher who lived in the 18th Century.

Give yourself five points for each correct answer. Here’s how to interpret your score: Zero to 30—you’re an atomic dud; 35 to 55—you can distinguish uranium ore from a hunk of coal; 60 to 80—you’re on your way to atomic science degree; 85 to 110—you’re cooking with atoms!

Exploding Three Mile Island

Think back. It hasn’t been that long ago. Pennsylvania looked like it might be blown off the map any minute, turned into a radioactive no-man’s-land forever. “Permanently uninhabitable” was the way they said it in the movie, The China Syndrome.

That’s the trouble. A lot of people said a lot of things. And a lot of it just wasn’t true. Not even close.

Take the hydrogen bubble that made all the headlines. Bubble, nothing. The implication was time bomb, ticking away. And that would’ve frightened anybody who didn’t have a degree in chemistry.

The fact is, that bubble couldn’t explode. Not by any stretch of the imagination.

To understand why, you have to understand how the hydrogen got there in the first place. And that takes some understanding of how the reactor at Three Mile Island was designed to work.

It’s the pressurized-water type, meaning the fuel core was cooled by keeping it submerged in water. H2O. Hydrogen and oxygen.

Heated by the core to more than 550 degrees, well beyond the boiling point.

What kept it from boiling was pressure, approximately 2,000 pounds worth. But on March 28th, last year, a relief valve on the pressurizer stuck open, the pressure dropped, and the water—the H2O— inside the reactor boiled into steam.

When that happened, the zirconium-alloy tubes housing the fuel underwent a chemical reaction. A kind of accelerated rusting that combined the zirconium from the tubes with oxygen from the water to form zirconium oxide.

That’s important, because with all the oxygen used up by the chemical reaction, the only part of the water left was hydrogen. The bubble. And what nobody bothered to tell you at the time was that without oxygen, hydrogen can’t explode.

On May 1st, more than a month later, the Nuclear Regulatory Commission admitted the scare was all a mistake. Roger Mattson, Director of its Systems Safety Division, told a congressional committee there “never was any danger of a hydrogen explosion in that bubble.”

That never made headlines.

And more than likely, neither will the fact that even if there had been a meltdown, it wouldn’t have spelled disaster for Pennsylvania. It couldn’t have.

First of all, the fuel core in the reactor vessel was surrounded by a containment building. Not just any building, an immense fortress with an enormously thick floor. Eleven feet of solid concrete reinforced with steel.

Second, for a molten mass to eat through it, that concrete-and-steel floor couldn’t be covered with water. But water is what’s used to cool the core. And when the relief valve on the pressurizer stuck open, sending several hundred thousand gallons shooting out, the law of gravity gave it only one place to go.

Down to the floor, right under the reactor vessel. Right in the path a molten mass would take.

That’s the fallacy of the meltdown theory. In spite of the overwhelming odds against it, if all systems failed, if the entire J core melted, if it got through the foot-thick steel reactor vessel in one piece and dropped to the floor below, it would’ve been stopped right there. Cooled by an ocean of water inside the containment building, not 20 feet from where the meltdown started.

As for any sudden burst of steam pressure that might be released when the molten mass hits the water, it wouldn’t be nearly powerful enough to rupture the walls of the building. Walls capable of withstanding almost twice as much force.

In other words, there was no way for significant radioactivity to reach the atmosphere outside.

The point of it all is that Three Mile Island and nuclear power itself deserve a fairer shake. A second look minus the hysteria, the hyperbole, the half-truths, and the untruths. They deserve a close, careful reading of the facts.

True, we’ve experienced the worst accident in the 22 years America has been using nuclear energy to produce electricity. But it wasn’t the apocalypse. No one died. And except for the stress of being scared stiff, no one was injured. Despite the equipment failures and failures in judgment, despite everything that went wrong, the safety systems worked.

What really exploded were myths.

Commonwealth Edison

One in a series of ads on the issue of energy in our community, paid for by the company and not published at our customers’ expense.

YEAR XIV…

…IN THE AGE OF NUCLEAR AND THERMONUCLEAR DEVELOPMENT

Interested in it? So are we!

For here at world-famous Los Alamos Scientific Laboratory, responsible for unleashing the terrifying power of the atom, we are now pioneering in harnessing this power for beneficial uses.

There is exciting adventure in the application of nuclear and thermonuclear energy to weapons, power and propulsion. Supporting these diverse activities here at Los Alamos are many challenging projects in basic physics, chemistry, metallurgy, mathematics and engineering.

Los Alamos needs men and women with imagination and research ability for permanent career positions. Interested? So are we!

Write us for an illustrated brochure describing the Laboratory, its delightful mountain location and its excellent housing and community facilities. Mail your request to
DIRECTOR OF PERSONNEL
DIVISION 512

los alamos scientific laboratory
OF THE UNIVERSITY OF CALIFORNIA

LOS ALAMOS, NEW MEXICO

Prelude to Atomic Energy

They’re moving mountains in South Africa. With the aid of Amberlite® ion exchange resins, sparsely distributed uranium is being selectively extracted from clay residues of gold mining. In Canada, on the Colorado Plateau, and in many other parts of the world, Amberlite resins are also easing the uranium refiner’s job.

The recovery of uranium is just one of the ways in which Amberlite ion exchange resins can serve in hydrometallurgy. Thorium and rare earth elements can be recovered from complex ores. Rhenium, relative of platinum, can be salvaged from refinery flue dusts. Dilute wastes from the conventional processing of cobalt and nickel can be scavenged for additional quantities of the metals. Even gold can be obtained from ores previously considered uneconomical to work.

Ion exchange, of course, is not restricted to hydro-metallurgy. Wherever ions in solution must be removed or replaced, ion exchange may provide the answer. The question is: what can Amberlite ion exchange resins do for you?

ROHM & HAAS COMPANY THE RESINOUS PRODUCTS DIVISION, PHILADELPHIA 5, PENNSYLVANIA

view additional pages

The Truth About… Our Weather and the A-Bomb

Many people, including weathermen, are inclined to believe that the atomic blasts are the cause of the vicious tornadoes, hurricanes, wind and rain storms that have swept across our country. MI Editors asked Eric Sloane, noted meteorologist, for his opinion. Here’s what he has to say.

THERE’S little doubt about our changing climate. The fierce winters of yesterday are disappearing, tornadoes and hurricanes are becoming more vicious and weather trends aren’t trends” any more. They can’t be depended upon. Just about anything can happen—and does.

If you are one of the many who wonder if the A-bomb is responsible for our queer weather, you can forget it. It isn’t so. What is the answer? It’s simply that we are riding on the tail end of a glacial age and our climate is shifting.

Let’s take a very simple proof.

Realize that not too long ago, before electric refrigeration, most of our large cities depended upon ice for their iceboxes. We don’t miss the ice today because we have refrigerators, but we would if we had to depend upon those very same lakes. They just don’t ice-over any more. Present-day New Yorkers who have never seen the Hudson River covered with ice find it hard to believe that once there was a regular ferry service over the ice to Staten Island. Many a five-year-old in “wintery” New England has yet to use a sled or throw a real snowball.

Our winters are milder and we are apt to overlook a comfortably warm winter season. But let there be a “day of the great blizzard” and everybody will remember it. Unpleasant weather leaves the greatest impression. Let winds and floods and storms increase and we immediately ask for a Congressional investigation to probe the possible effects of atomic radiation on weather.

If you are still upset, however, and feel you must worry about the distant future of mankind, forget the weather effects of atomic bombs and wonder what would happen if the ice reservoirs of Greenland and all the polar regions let go in one fast melting spree. The level of our oceans would rise about 200 feet. All our coastal cities would be wiped out and civilization would have to retreat to the highlands. As a matter of fact the polar icecaps are already receding at the rate of some 500 feet a year, causing climatic changes and raising the level of the sea about an inch during the last century. This is a sign of things to come.

The glaciers and ice reservoirs began their retreat about 20,000 years ago and by 5,000 B. C. the weather had become much milder. Green forests spread into the northlands where they exist today. After the twelfth century however, the weather cycle swung low and the climate became more severe. Winters became longer and the glaciers reached their maximum during this “Little Ice Age” from 1650 to 1850.

Since 1850 the glaciers have been retreating under a climate of shorter winters and warmer summers. Despite the fact that our snowiest winter was but five years ago, you may discount that as being no more than a break in the cycle; the trend toward warmer climate persists. Whether it will fluctuate, become stronger or weaker, is all within the fancy of time. Certainly none of us will live to see such drastic changes as the melting of the icecaps.

A tornado has no part in the machinery of climate. Rather it is the accidental loose nut that flies off the machine or the backfire of an otherwise normal storm cycle. A tornado is like a whirlpool where two tides meet. You can get the effect of one by rolling a pencil between your two palms. Each hand represents a different air mass; the pencil which turns rapidly but moves slowly up or down each hand acts just like the long funnel of a twisting tornado. Try it and see.

When a warm moist air mass meets a cold front head-on, the motion of the two different kinds of air (like the two hands), causes friction and extreme low pressures. Once a low pressure area funnels into a definite pattern, it will spiral earthward as a tornado “cloud” or funnel. The waterspout is just a tornado over the water and although most people think the waterspout contains water being sucked up from the sea, it is merely a cloud being formed by condensation within whirling air. The sea water sucked upward in a waterspout seldom rises more than two or three feet and when the spout disappears, tons of sea water do not fall back into the sea, but the fresh water forming the cloud just disappears back into the atmosphere again.

Whereas a 500-mile whirlpool (hurricane) will blow down a house, a 1,000-foot whirlpool (tornado) will suck down a house. Such concentrated low air pressure outside the house will make it explode outward, blown apart by high air pressure within the house just as an automobile tire will also explode outward into the low pressure of a tornado.

The drawing shows in simple form a tornado forming along a cold front. To indicate the air mass which the “front” is the front of, you would need a magazine page 100-feet wide. The frontal storm machinery is huge, many times larger than the storm itself and much too large an area to be formed by the aftermath of an atomic explosion.

Usually, about two days after a bomb blast in Nevada, radioactive particles fall on the east coast. This fact, along with unusual weather, is what has startled many people including meteorologists into wondering about the effect of atomic blasts on our weather. Weathermen know that rain cannot occur in absolutely clear air—that tiny particles are necessary as nuclei for the raindrops to form around. It is true that a great blast does push dust into the substratosphere where there are express air jets of global wind to carry it elsewhere. On April 6, 1953 an A-blast was set off at Yucca Flats, Nevada. On the following two days a rain cloud bearing irradiated dust covered the east coast. This is not startling, however, for on May 2 New York had a rainfall containing red dust from windstorms in Texas. In other words it is perfectly natural for dust (irradiated or not) to be carried elsewhere and aid in the formation of rain. Even smoke particles might result in being nuclei for rain. So, generally speaking, the clouds of an atomic explosion are not “thunder clouds.”

As the atomic scientists put it, “there is no evidence that the explosion has been followed by anything but a passing local downpour;” In other words, that the particles in the mushroom-shaped cloud acted as dust around which droplets of moisture condensed just as rain makers sow the clouds with crystals of silver dioxide for the same purpose.

Any sustained change or a trend in weather is so large an affair that a local disturbance, even atomic-bomb size, seems ridiculously small. It is like expecting a spoonful of hot water to noticeably change the temperature of a tub full of cold water. A frontal storm which usually brings our rain may be likened to the foam at the prow of a great ship. Like the vessel behind the bow-wave, the warmer (or colder) air mass behind the storm is many thousands of times bigger than the storm itself. For example, our severe summer thunderstorms are about ten miles wide but the cold air mass that causes the commotion may be a great blob of cooler air 500 miles in diameter.

As for our climate becoming warmer, even the heat generated by our large cities plus the many thousands of square miles of denuded forests that have been replaced with heat absorbing concrete might definitely change the average temperature of the country more than the heat generated from any A-bomb.

Although man can nick off a degree or two here and there or coax rain out of a cranky rain-cloud, nature is still the boss of the atmosphere.

The bombs won’t change your climate.— Eric Sloane

view additional pages

These Dogs Are Really “Hot”

Radioactive beagles are pointing the way to better safety devices for workers in atomic energy plants.

A PACK of 300 sad-eyed, floppy eared beagles are serving as canine guinea pigs in an unusual University of Utah project designed to investigate the hazards of industrial radioactivity. Financed by the Atomic Energy Commission and directed by Dr. John Bowers, the studies will show what happens to bone and tissue when radioactive substances are injected into the dogs. Beagles were chosen for the experiments because they are anatomically close to human beings, have a sound genetic pattern, ideal disposition and are easy to handle in the research laboratory.

Radioisotopes used in the injections are radium, plutonium, mesothorium and radiothorium. These materials have a particular affinity for bone structure. Lodging in the bones, the radioactive particles continue to emit rays which affect the marrow—part of the “blood factory” of the body—and eventually are expected to produce tumors.

view additional pages

A-POWERED TRAINS IN GLASS TUBES

They’ll give airliner speeds plus weather-free reliability.

By Frank Tinsley

THE train of the future, whipping passengers vast distances through continent-girdling tubes at speeds and in comfort far surpassing that of modern air travel, is no longer merely a dream in the minds of our more imaginative designers and engineers. This old idea (New York’s first working subway train was sucked through a tube) has been brought well within the realm of probability—and the hero of this advance is, as has so often been the case in the history of technology, a new material.

A crude form of this material has been serving man since the dawn of history. Glass, commonly thought of as that brittle stuff that boys like to smash with baseballs and slingshots, is in this generation being brought to such strength, lightness and flexibility that the glass industry is now looking toward a new era, not so far off, when bridges, buildings and car bodies will be built of glass that is stronger and lighter than steel. And from Oscar G. Burch, Vice President in charge of research for the Owens-Illinois Glass Company, a very sound and serious-minded engineer, comes the word that the tubed train may some day take over the long haul business.

Long distance trains, according to Mr. Burch, may abandon today’s exposed tracks and rocket across country in glass tubes, propelled at airplane speeds by compressed air. He also envisions glass-sheathed spaceships and entire cities built beneath air-conditioned domes of lens-clear crystal. So far, says Mr. Burch, we have achieved a paltry one per cent of the theoretical strength and use potential of glass. As small an increase as ten per cent will be ample to turn his seemingly bizarre predictions into solid actuality!

As far as we know, however, Burch’s test-tube railroad is an entirely new concept, and one which intrigues your editors. We have pondered its engineering problems and possibilities and herewith present our own preview of tomorrow’s transparent trains.

First of all, it must be emphasized that Mi’s tubular train will not replace today’s open-face local and commuter services. It is intended, rather, to complement these by adding airplane speeds to long distance railway runs. The possibilities of its fast, round-the-clock service, unchecked by snow or storm, should reverse present trends in passenger travel and give the airlines a real run for their money. Zipping through its glass sheath from New York to Florida or coast-to-coast at 300 mph or better, our crystal flyer can combine the distance-devouring zoom of aerial flight with the safety and comfort of surface travel.

While conceding the practicability of structural glass for tubular railroad tracks, we could not however, go along with Mr. Burch’s method of propulsion. The use of compressed air, we felt, in- volves too many problems of generation and control. A string of power stations would have to be spaced along the line to evacuate the tube ahead of the train and build up propulsive pressures behind it. In addition to the expense and complication, this system would limit the operating headway by preventing trains from following one another at reasonably frequent intervals.

There was also some question as to the public’s willingness to be shot along in devices not under direct human control. Your editors concluded therefore, that each individual train should be driven by an engineer and propelled by a self-contained powerplant capable of controlling the pressures generated by its passage through a closed tube.

The most obvious answer to these specifications is the jet engine. With an airplane-type nose intake, this could suck in air from in front of the train and blow it out behind. By thus creating a partial vacuum ahead and pressure astern, our jet could either raise the speed or reduce the power requirement with a consequent increase in the vehicle’s overall efficiency.

There is, however, a serious objection to the conventional jet engine operating on a petroleum-base fuel. It expands the working fluid—air—by mixed combustion and the gases expelled from its tailpipe would soon taint the air in the tube. Succeeding trains would rapidly concentrate the carbon monoxide content to a poisonous level. Therefore, the standard chemical fuels were out. We had to find a heat source which could expand the working air without contaminating it. In this atomic age we had not far to look.

The new type of atomic heat generation unit in which the reactor core is surrounded by a built-in heat exchanger and the whole encased in composite shielding, will eventually be light and compact enough for locomotive use. This is the plant for our tubular train. From it, molten sodium is piped through shielded ducts to a cylindrical heat transmitter enveloping the jet engine’s “combustion chamber.”

Compressed air entering the chamber is heated and expanded without coming into physical contact with the sodium. It then blows out the tail-pipe as clean as it came in. This operating air, as previously noted, has been drawn into an intake beneath the nose of the leading unit and carried the length of the train through ducts built into the lower sides of each car. Between the cars, flexible connectors—larger versions of today’s air brake hoses—span the coupling gaps.

Upon reaching the rear power unit, the air flows into twin jet engines mounted on either side of the reactor. There it is compressed, expanded by atomic heat and ejected rearward to produce the propelling thrust.

Mi’s train differs radically from today’s iron horse in that its wheels and tracks are used only at low speeds and stops and function chiefly as a landing gear. While loading and unloading in a station, the wheels are lowered to bear the weight of the train. After starting, they continue to carry the weight to a diminishing degree as the train moves forward. During this gradual acceleration, the air ahead of the train is compressed to an increasing degree and forced to flow backward around the cars through the space between the trains outer surface and the tube’s inner wall.

When the train reaches a certain speed, this surrounding layer is compressed to a point where it supports the vehicle’s weight. Thereafter, the train retracts its wheels and literally “flies” through the tube like an airplane test model in a wind tunnel. Having no “hot box” wheel bearings or track forces to consider, airline speeds are easily attainable.

In designing the train itself, your editors drew liberally from ACF Industries’ high speed Talgo Train. With an unusually low center of gravity, short, close-coupled car units and steerable, automobile-type wheels, the lightweight Talgo can snake around turns at 80 mph or more. All these characteristics are essential to tube transit, where smooth-surfaced curvability is a must. About the only mechanical changes necessary were to make the wheels retractable and provide a bottom “keel” to prevent lateral rotation within the tube. Like the Talgo, the basic MI car is 60 feet long, broken into three articulated units. Each unit is equipped with one pair of rear wheels, its forward end pivoting on the pair ahead like the body of a trailer truck.

Here, however, the Talgo resemblance ends. Circular in section except for the bottom keel, Mi’s cars are double-decked to gain floor space and make maximum use of interior space. The vestibule platforms and doors are set midway between the levels, with short stairways leading up and down to the two decks. They are designed so that the platforms rest on top of the wheel wells, thus conserving space. There is an adjoining lavatory on the lower level.

In line with the latest trend in air travel, the cars are divided into two price classes. The lower deck offers coach service with a maximum-capacity arrangement of forward facing seats in conventional railway style. They are ultra-modern, individually tilting chairs with adequate leg room, set one step above a sunken central aisle. Windows are the continuous-strip type of steel-strong, structural glass and form the side panels of the car. Above are individual reading lights and racks for luggage and clothing.

The upper deck features deluxe, chair-car accommodations which like its present railroad counterpart, is a reserved, extra-fare service. Paired seats are placed diagonally to fully exploit the vista-dome windows. They are set far enough apart to permit full reclining position for night runs. The triangular floor areas on each side enable the traveler to enter or leave without disturbing his seatmate. Porter or hostess service will be provided.

The first-class diner is on the upper level of the unit adjoining the rear power car, with a capacious kitchen and pantry positioned above the engine room. The atomic heat which drives the train and generates its auxiliary electric power, may also be tapped for cooking. A dumbwaiter connects the upper pantry with a similar one below. This serves the more modest priced grill car on the lower level. Both diners are inter- connected and the traveler can take his choice. Placing the eating facilities at the rear will present no undue hardship as trains will be limited in length and scheduled for frequent runs on short headway.

This is MI’s visualization of Mr. Burch’s tubular railway. It is a composite of several research projects now under intensive development and although it may seem like a pipe dream now, the imminent perfection of structural glass and aircraft atomic power-plant will suddenly catapult it into the realm of solid practicality. As for the Talgo Train, that little gadget has been running for half a decade now, speeding passengers at a safe 100 mph clip.

The tubed train is only one of the startling innovations in the use of glass envisioned by the researchers of Owens-Illinois and other manufacturers. The diminishing supply of metal resources makes it imperative that new construction materials be found, and glass-makers are convinced that all the properties of metals can be developed in glass.

They see the day fast approaching when the pressure of increasing world population will lead to the erection of entire glass cities in desert and arctic regions—cities constructed on glass columns, enclosed in glass domes, heated and air conditioned by atomic power. Inside the glass cities of the future will be glass homes, glass furniture and glass cars, planes and trains—all combining the structural strength of steel with the transparency and beauty of crystal.

But before these things exist, it’s possible you may see Mi’s A-powered trains in glass tubes, zipping from coast to coast at 300 mph—a fitting beginning to our new series on the Amazing Marvels of Tomorrow!

What does Atomic Energy really mean to you?

Dramatic new developments in medicine, agriculture, and industry promise long-time benefits for us all

Scientists have long known that the secret core of the atom concealed vast stores of concentrated energy. Evidence that man had unlocked the secret came with the atomic bomb. Then came the task of developing methods to release this unbounded energy slowly, gradually, in ways of lasting benefit to all of us.

ISOTOPES AN EXAMPLE—When uranium atoms are split they emit a barrage of highly active particles. Certain chemicals placed in this barrage become radioactive and shoot off particles from themselves. Substances thus treated are called radioactive isotopes.

When these chemicals are made radioactive their paths can be traced through plants and animals, showing the organs they affect. This may increase our understanding of the processes of life itself.

FUTURE UNLIMITED —Atomic energy is also proving useful in industrial research and production. It promises to be even more valuable, however, in providing concentrated power for transportation, home, and industry.

UNION CARBIDE’S PART-From the beginning UCC has had a hand in the mining and treatment of uranium ores, the development of engineering processes, and the production of special materials for the atomic energy program. Under Government contract Union Carbide manages and operates the huge research and production installations at Oak Ridge, Tenn. and Paducah, Ky.

All of this activity fits in with the continuing efforts of the people of Union Carbide to transform the elements of the earth into useful materials for science and industry.

FREE: Learn more about the interesting things you use every day. Write for the 1953 edition of “Products and Processes” which tells how science and industry use the ALLOYS, CARBONS, CHEMICALS, GASES, and PLASTICS made by Union Car bide.. Ask for booklet D.

Union Carbide AND CARBON CORPORATION
30 EAST 42ND STREET NEW YORK 17, N. Y.

UCC’s Trade-marked Products of Alloys, Carbons, Chemicals, Gases, and Plastics include Synthetic Organic Chemicals • Eveready Flashlights and Batteries • National Carbons • Acheson Electrodes • PYROFAX Gas ELECTROMET Alloys and Metals • Haynes Stellite Alloys • Prest-O-Lite Acetylene Dynel Textile Fibers • Bakelite, Krene, and Vinylite Plastics • Linde Oxygen • Prestone and Trek Anti-Freezes

view additional pages

IF Atomic Fuel Were Shared…

The world would be healthier, wealthier and wiser, say AEC scientists, discussing President’s daring proposal to United Nations.

editor’s note: President Eisenhower’s dramatic proposal to the United A at ions that a world pool of fissionable materials he created for peaceful purposes had no greater appeal to any hearts and minds than those of nuclear scientists. Popular Science Monthly invited some of them, on the staff of the Atomic Energy-Commission’s labs at Brookhaven, N. Y., to tell yon what they think of the plan’s potentialities. Their discussion, recorded on magnetic tape, is transcribed here. The various speakers are: William A. Higinbotham, Harry Palevsky, Drs. Clarke Williams, Marvin Fox and Charles P. Baker, physicists; Mrs. Beth Baker, a chemist; and Wesley S. Griswold, of PSM’s editorial staff.

MR. GRISWOLD: What do you people think of the President’s plan to pool fissionable materials for peaceful uses?

Dr. Fox: I think it’s brilliant—a stroke of genius to solve this whole dilemma that has confronted us for the last half-dozen years.

Mr. Palevsky: It provides a central focal point that serves a very necessary purpose. It starts us off.

Dr. Baker: The Acheson-Lilienthal proposal, in 1946, was a brilliant proposal, but in order to get anywhere, you have to start. And with that proposal you had to start by taking off all your clothes and jumping in. Whereas in Eisenhower’s proposal, you say, “Take off your coat, loosen your tie, and sit down. ” There are many people who will do this that wont go the whole way.

Griswold: If you were given the task of setting up such a pool, would you anticipate getting large amounts of fissionable materials, or small amounts? Mr. Higinbotham: The fact is that no countries except Russia and the U. S. (which are well stocked) and England and Canada have the capital to buy—or, as a matter of fact, have access to—a substantial amount of source materials.

You see. thorium is useless until you’ve gone a long way with uranium and its products. And the U. S.. Great Britain and Canada have virtually cornered the free-world market in uranium.

Palevsky: So the three of us and Russia control all the source materials, except for truly trivial quantities.

Higinbotham: The U. S. and Russia control a lot of materials, but they don’t own them. I think the first step is to get these two major parties to loosen up on their controls, so that other people can play around.

I’m thinking of natural uranium and thorium ores—source material.

Griswold: You think, then, that it would be ores that would be contributed to this pool, and not enriched stuff?

Higinbotham: Yes.

Grisuold: How would you ship the materials to the pool?

Higinbotham: I suspect that you are thinking of this pool as a big concrete building somewhere, loaded with radioactive stuff. It seems to me that what Eisenhower contemplates will be a holding company, like the AEC. The stuff will be stockpiled all over the world. It will go by the pound or the truckload or the shipload direct from the donor to research laboratories in different countries all over the world.

Griswold: Is it dangerous to ship? Would it require shielding?

Fox: Not in ore form.

Griswold: What does the stuff look like?

Fox: Well, uranium is shiny silver when freshly made but tarnishes to brown or black quickly when it’s exposed to the air.

Griswold: I’ve heard that it can be obtained in fairly small ingots, almost the size of flashlight batteries.

Fox: You can get it in any size you like.

Griswold: What countries besides the ones you have already mentioned would be likely to have surplus fissionable materials for the world pool?

Baker: I think you should include the Belgian Congo, South Africa and Czechoslovakia—if you can distinguish that country from Russia.

Higinbotham: You’d also include India and Brazil, wouldn’t you?

Baker: Oh, yes.

Higinbotham: India and Brazil would most assuredly be interested in the power potentialities of a world atomic pool. Brazil is peculiarly poor in water resources. The waterfalls are a long way from the coast. The Amazon is flat for many, many miles inland. I think the Brazilians are working small streams mostly.

As a result, Rio and Sao Paulo, the two biggest cities—about 200 miles apart with decidedly mountainous country between—have a common power supply. And they are so hard up for electricity that the different sections of the cities are shut down in succession.

Griswold: Is it possible that we can have smaller atomic power plants than any yet built—plants that could be used, say, to run planes and trains?

Fox: Oh, yes.

Dr. Williams: Especially Russian trains, which are broader gauge. [Laughter. ] Griswold: But not small enough to run automobiles?

Higinbotham: Well, the only possibility in this line is that someone might design a really good battery that you could have charged at an atomic power station, and then run your car by electricity.

Baker: There are other ways. If you had cheap power you could store it chemically by taking water and carbon dioxide and making gasoline out of them, then pouring the gasoline into your car. [Laughter. ] Well, if you had cheap power, you could do this.

Palevsky: That’s true. If you can make cheap power, there are just unlimited processes that could be developed.

If you can reduce the cost of power by, say, 20 or 30 percent, I think that many new industrial processes would just spring up overnight. They will then be feasible.

Griswold: How could atomic power be useful in barren lands—like Arabia or the Australian desert?

Palevsky: Why, in making fertilizer. You need power to make fertilizer.

Griswold: Yes, but what about water?

Water would still be the essential ingredient, wouldn’t it?

Baker: If you have the energy, you can demineralize sea water. If you have the energy, you can also pump it as far as yon like, if you’re willing to pay for it.

It’s not a matter of discovering any fundamentally new principle. It’s a matter of getting the science, the technology and the economics together.

Palevsky: Even in those desert regions, I think if you go down far enough, you get water. It just happens to be uneconomical to pump it now. But cheap power from atomic energy would easily make the pumping job feasible.

Griswold: Have we yet come up with any practical atomic explosive for changing the course of rivers, or for changing the course of hurricanes or tornadoes?

Mrs. Baker: Well, you’d pollute your rivers, for one thing.

Palevsky: And if you dropped an atomic bomb into the eye of a tornado, you’d scatter lethal radioactivity all over the countryside.

Baker: The Eastman Kodak Company would certainly be unhappy. [Laughter. ] Griswold: If the proposed atomic pool is going to exist in several different places, scattered throughout the world, how can it feasibly be guarded?

Higinbotham: First, is it worth guarding? Probably all the material contemplated for the pool will not be enough to make a single atomic bomb. And when the atomic bombs in the world already are counted in the hundreds or the thousands, material that could possibly make one more is not really important.

Griswold: Isn’t it true that, with the right kind of reactor and the necessary raw material, in the course of making atomic power you also make plutonium?

Higinbotham: Yes, but it isn’t until you have really big power plants that the amount of plutonium you are going to produce in a year will be significant.

Baker: Besides, in order to make this plutonium useful, you would have to run your plant in a particular way and it would involve certainly an equivalent plant to extract the plutonium. In other words, if you went and looked at the power plant, you wouldn’t need to be a detective to tell if people were Africa, and now had plutonium, where would you send the plutonium?

Baker: Send some back to South Africa, so that they can start their power plant.

That is, I would think that if the pool delivers uranium to somebody and they use it in a power plant, and use the power for their benefit, then the plutonium which they make incidentally should, of a certainty, belong to the pool and might be sent to help make a quart of milk for every Hottentot, or whatever else seems to be a worthy undertaking.

Mrs. Baker: Essentially, then, you could just rent the material, and then pay it back to the lender.

Higinbotham: It would be ideal if, when we allow another nation to take from the international pool certain material that had been allocated to us, we would also permit that nation’s scientists to visit our laboratories, see our reactors, learn our techniques. Some of our scientists, too, would be expected to go to those countries and help them get started on their research—let them in on our know-how.

Williams: The information is fully as important as the materials, if not more so.

Higinbotham: This proposal of Eisenhower’s really will be something that will be awfully hard for the Russians to turn down.

If you can get a start at talking on a practical level about these problems of the exchange of information and people and cooperation, there will certainly be an entirely different atmosphere from the one we’re presently living in.

And one could hope that out of these discussions would come something at least as attractive as the Eisenhower proposal, and that this would be the beginning of breaking down the iron curtains that exist not only around Russia but around a good many of the rest of us, too. end

It may or may not be significant that, since early spring, no accounts of research on nuclear fission have been heard from Germany — not even from discoverer Hahn. It is not unlikely that the German government, spotting a potentially powerful weapon of war, has imposed military secrecy on all recent German investigations. A large concentration of isotope 235, subjected to neutron bombardment, might conceivably blow up all London or Paris.

view additional pages

Two Elements For One

The Most Important Scientific Discovery of the Present Year is also the Biggest Explosion in Atomic History … Splitting the Uranium Atom

THE Fifth Washington Conference on Theoretical Physics was sitting in solemn conclave when the news broke. Professor Nils Bohr of Princeton and Professor Enrico Fermi of Columbia rose to open the meeting with an account of some research going on in a Berlin laboratory.
Professors Bohr and Fermi are Nobel Prize winners both, and their names are as well known to scientists as Toscaninni’s is to music lovers. The Conference therefore expected something extra special. They weren’t disappointed.

It was January 26, 1939. A few wees before, at the Kaiser Wilhelm Institute in Berlin, Dr. Otto Hahn, a distinguished German physicist, had obtained an utterly unexpected result from some more or less routine experiments. Following the original example of Professor Fermi, Dr. Hahn and his co-worker, F. Strassmann, had for many months been bombarding uranium with neutrons and studying the debris left by this atomic warfare.

It would not have surprised them at all to find radium as one of the products. In fact, they had done so before, or thought they had. Radium and uranium are near neighbors in the table of elements, and it is nothing new for scientists to transform one element into another close to it in weight and electric charge.

But it was news, and big news, to discover barium among the debris — barium, which is only a little more than half as heavy as uranium. It meant that the neutron bullets had succeeded not merely in knocking a few chips off the old block, but in blowing the whole atom asunder with a terrific explosion.

The theoretical and practical import of Hahn’s discovery may not be immediately obvious to the laymen. The article will attempt to interpret its significance in later paragraphs. But on the scientists, the news had the same effect as the tidings of gold in California had on the Forty-niners. They flew to their laboratories to find the treasure for themselves.

A few insiders had already jumped the gun ahead of the Conference and of the rest who learned of the discovery through the newspapers. In Copenhagen, Dr. O. R. Frisch and Professor Lise Meitner, who had previously worked with Hahn on the same problem, had verified his results ten days earlier. A group of Columbia University physicists, including Fermi, independently thought up and carried out a similar experiment by January 25, the day before the Conference. By the time the meeting wound up its affairs January 28, three more laboratories — at the Carnegie Institution of Washington, Johns Hopkins, and the University of California — joined the chorus of confirmation. In a word, Hahn was right. Uranium, and thorium, too (thorium is also among the heaviest elements), had been split in two by neutron bombardment.

THE phenomenon was quickly dubbed “nuclear fission,” and in the months ensuing since its discovery, nuclear fission has grabbed the spotlight from the “heavy electron” sensation of 1937-8. Dozens of the world’s top-flight physicists have been busy as bees, roaming the clover of a new field of research.

The first task of the investigators was to get a picture of what had happened. Dr. Frisch and Miss Meitner promptly supplied a pretty good one.

The nucleus of an element, they pointed out, is now thought of as an aggregation of protons and neutrons packed together into an inconceivably small space. The number of protons, or units of positive electric charge, accounts for the chemical behavior of the element. Neutrons are units of weight and have no charge. Together the neutrons and protons make up the mass of the nucleus. The simplest nucleus is the single proton belonging to the lightest element, hydrogen. Going up the atomic scale, adding one proton and a varying number of neutrons for each successive element, we arrive at last at uranium. This heaviest of elements is invariably characterized by its 92 protons; in its commonest form it contains 146 neutrons as well, giving it a total weight of 238. Two other forms, weighing 235 and 234, also occur in small quantities. These are called the three natural isotopes of uranium, and are distinguished by the shorthand symbols U238/92, U235/92, and U234/92.

Now all the known elements heavier than mercury — that is, thallium, lead, bismuth, polonium, radon, radium, actinium, thorium, protactinium, and uranium — have isotopes that are naturally radioactive. Their nuclei are so complicated that occasionally one will spontaneously simplify itself by shooting off a particle.

We can picture the process nicely if we imagine for a moment that the radioactive nucleus is like a drop of water, composed of many molecules. One of the molecules near the surface somehow acquires a little more energy than its fellows and evaporates.

The stage is now set to return to Dr. Frisch and Miss Meitner, whom we left some paragraphs ago. Their conception of the nuclear fission process continues the analogy of the drop of water. Suppose the H20 molecules are violently agitated by a source of energy outside the drop. Instead of evaporating gradually, the drop splits in two. Similarly, a uranium nucleus, stimulated by the impact of a neutron bullet, may divide into two smaller nuclei of roughly equal size.

These fragments are in themselves unstable, and quickly disintegrate to form still other nuclei. In fact, a whole series of transmutations generally follows the fission of uranium or thorium. Since Hahn first found barium among the products, he and other investigators have identified antimony, tellurium, iodine, xenon, caesium, and lanthanum in one group; bromine, krypton, rubidium, strontium, and yttrium in another, with many possible additions.

The explanation is simple enough. The original fragments contain too many neutrons in relation to their proton content, and must get rid of them to achieve a stable form. One of two things happens. The nucleus may simply expel a whole neutron, reducing its weight by a unit. Or one of the neutrons may be converted into a proton plus a negative electron inside the nucleus, which promptly ejects the electron. In the latter case, the nucleus remains approximately the same weight but acquires an additional positive charge, thus becoming a chemically different element. Experiments have proved that both these types of disintegration actually do take place.

No one knows yet whether the same two original products are always formed when uranium divides, or what they are. But if one of the fragments is barium, with 56 protons, the other must have 92 minus 56, or 36, protons, which would make it an isotope of the gas krypton.

If the barium tries to stabilize itself by emitting an electron, it becomes a lanthanum isotope, which may in turn convert itself into cerium by electron emission. The krypton also disintegrates in the same way, successively becoming rubidium, strontium, and perhaps yttrium and zirconium. We can show these chain reactions by a formula where the sub-scripts represent the number of protons of the products:
Ba56 -> La57 -> Ce58 -> Kr36 -> Rb37-> Sr38 -> Y39 -> Zr.40
Again, if the two original fragments are strontium and xenon instead of barium and krypton, we may have the following chain reactions:
Sr38-> Y39-> Zr40
Xe54 -> CS55 -> Ba56 -> La57 -> Ce58

In a discovery like this in the realm of pure science, it is always easier to see the theoretical importance than to find a practical application. The fission of uranium has provided a field day for the physicists who like to take atoms apart and find out what makes them tick. It adds a new chapter to their knowledge of the nucleus — the forces that hold it together, the collective behavior of its constituent parts, its reaction “under fire,” its destiny.

In addition, it clears up a mystery of long standing, dealing with elements heavier than uranium. When, in 1934, Fermi began his experiments with uranium, he soon found that negative electrons were always emitted under neutron bombardment. We know now that they are usually the products of the chain reactions just described; but at that time nuclear fission was not even dreamed of. Fermi naturally concluded that the uranium nucleus captured the neutron, converted it into a proton and expelled an electron.

Here, then, was a supposedly new element with 93 protons, unknown to nature. Moreover, this new element seemed to emit another electron to form another new neucleus of 94 protons. These were called “transuranic” elements, and up until lately they were a headache to the numerous investigators who worked on them. The latter kept finding more and more transuranics; and when they studied their chemical properties they found inexplicable variations. Last November, just a few weeks before Dr. Hahn stumbled on the real secret, he announced that he had found at least 16 different kinds of nuclei resulting from neutron bombardment of uranium. Some of them, indeed, behaved chemically like barium, lanthanum, and other light elements, but they were thought to be isotopes or isomers of heavier elements such as radium. (Isomers are nuclei having the same total weight but different chemical properties. Isotopes have the same proton content but varying total weights.)

When the announcement of nuclear fission came, it was immediately realized that the electrons were not in general emitted by the uranium nucleus itself but by its lighter fragments. The mystery of “transuranic elements” was practically solved. It does seem, however, that a neutron bullet occasionally fails to give its target quite enough energy to divide; the uranium isotope disintegrates by electron emission and really does form a new element with 93 protons. But one such problem child is far better than 16.

So much for the theoretical significance of nuclear fission, far-reaching though it is. It is pretty hard to amass as much weight on the practical side of the balance. But our imaginations are immediately seized by the terrific amount of energy liberated when a single uranium nucleus explodes. The two fragments fly apart activated by some 200,000,000 electron volts — a total far greater than that associated with any other atomic phenomenon except cosmic rays.

The tabloids love to write of blowing up the world with a gram of matter, and it’s not such a sensational idea as one might think. Even a tiny mass has an enormous potential of energy if it could but be freed. It is just such a conversion of mass into energy that speeds the fission fragments on their way.
The weight of any nucleus is never quite equal to the sum of its individual protons and neutrons. A small proportion of their mass, called the “packing fraction” or “mass defect,” is somehow transformed into the force that holds the nucleus together. Otherwise the positively charged protons would all repel each other and scatter in every direction.
The packing fraction for uranium is, because of its large number of particles, greater than that for the simpler elements into which it divides. This difference in energy is released with the two fission fragments.

OF course, 200,000,000 volts is an astounding energy compared with the size of the bodies which possess it. But for practical purposes it is absurdly small, amounting only to about three ten thousandths of an erg. In more everyday terms, it would take 25,000 billion fissions per second to produce one horsepower — figures which dwarf even the national budget. The very best a laboratory can do so far is produce a few hundreds per second.

If atom smashing could be made more efficient, power production by means of nuclear fission would not be beyond the realms of possibility. But under present conditions, the process is as inefficient as removing the sand from a beach a grain at a time. Or, more graphically, it is like shooting with buckshot at a netwood of beads strung yards apart. The size of the target is comparable with the size of the projectile, the empty space between targets is enormous compared with the diameter of either, the stream of bullets cannot be well controlled or aimed, and therefore it is much more probable that the neutron projectile will fly past a uranium nucleus than to score a direct hit and be captured. In fact the chances are thousands to one against fission taking place.

Neutrons have proved themselves more efficient atom-busters, however, than other projectiles like protons or alpha particles, which are positively charged and hence repelled by the positive nuclei. To get a stream of neutrons, a preliminary bombardment must take place. One common method employs the radioactive gas radon, which spontaneously emits alpha particles (helium nuclei with double charge and mass four). The alpha particles are allowed to fall on a sheet of beryllium, where they join with the beryllium nuclei to form carbon plus neutrons. The reaction is shown by the formula:
Be9/4 + H4/2 -> C13/6 -> C12/6 + n1/0
where the superscripts are the atomic weights and the subscripts the charge.

The stream of positive particles from the cyclotron may also be used to bombard beryllium and thus produce neutrons. The high energy and great number of cyclotron particles make them more efficient neutron makers than the natural radio-alpha particles.

Once created, the neutron beam is directed against a uranium target. The products are studied in various ways. If the investigators want to find the energy of the fragments, the target is placed in an ionization chamber, filled with a gas at low pressure. The fragments rip through the gas atoms, disrupting their outer electron structure to form ions. The gas ions are drawn to a wire where they constitute a tiny electric current, and the magnitude of this current gives a clue to the energy of the fission products.

If the experimenters want the range of the particles — that is, the distance they travel before their kinetic energy is all used up — they may choose a Wilson cloud chamber which automatically photographs the track of ions the nucleus leaves behind it.

If they want to know the number of fissions occurring in a given time, they have an electric counter at their command, based on the same principle as the ionization chamber. A modification of the same instrument is used to look for electrons or neutrons emitted in the fission process or in the chain reactions that follow.

The problem of identifying the prod ucts is a somewhat different one, and is complicated by the large number of elements which may be formed. Here the debris is collected on a sheet of Cellophane or paper placed close to the uranium target. Each variety of isotope on the sheet has a definite rate of disintegration — it may be anywhere from a fraction of a second to several days — and this time is characteristic of the element to which the isotope belongs.
To measure this period of decay, the collecting paper is placed near an electric counter. If the activity of one product decays to half its original value in 87 minutes, for example, that product is immediately known as an isotope of barium, Ba139/56, which is known from other experiments to have a characteristic “half life” of 87 minutes. The difficulty of this method of identification is, of course, in separating the half-live when two or more elements are decaying together; and also in classifying a half-life belonging to an isotope previously unknown.

Another method of studying the products is to perform the experiment under water, then analyze the water chemically. Suppose we suspect that a few nuclei of radioactive lanthanum are present. This is too small a quantity to separate directly. But if a larger amount of a stable lanthanum compound is added to the water, both stable and un-stable lanthanum atoms can be precipitated out. If this precipitate is then shown to be radioactive, we have proved our suspicion was correct. Similarly the water can be tested for radioactive barium by adding a stable barium compound and so on.

STILL a third attack on the problem of identification has been made by Philip Abelson at the University of California. He had been studying the natural X rays from the supposed “transuranic elements”; and put on the right track by the discovery of nuclear fission, he quickly showed that these X rays had wavelengths characteristic of iodine and tellurium.

Research along all these lines is proceeding at breakneck speed. Experiments similar to those with uranium have been performed on thorium (Th232/90) with similar results, except that only fast neutrons are effective in splitting the thorium nucleus, while both fast and slow work well on uranium. Other heavy elements, such as gold and tungsten, show some slight tendency to undergo fission.

Fermi and others have been trying to determine which of the three uranium isotopes are involved, and how the process is related to the speed of the neutron projectiles. Duke University scientists are investigating gamma radiations connected with fission, and the University of California is piling up data in all branches of the research. Bohr at Princeton, Solomon in Paris, and many another are concerning themselves chiefly with theory.

Irene Curie and P. Savitch, who were responsible for much of the ground work enabling Hahn to identify the products of his fission experiments, have been carrying on the classification work in Paris. Joliot, as well as groups of physicists at Columbia, the Carnegie Institution, and Cambridge University, have concentrated on the study of secondary neutrons emitted at the moment of fission and in later reactions.

The latter problem brings up an interesting and rather disturbing aspect of the case. These secondary neutrons constitute a fresh supply of “bullets” to produce new fissions. Thus we are faced with a vicious circle, with one explosion setting off another, and energy being continuously and cumulatively released. It is probable that a sufficiently large mass of uranium would be explosive if its atoms once got well started dividing. As a matter of fact, the scientists are pretty nervous over the dangerous forces they are unleashing, and are hurriedly devising means to control them.

It may or may not be significant that, since early spring, no accounts of research on nuclear fission have been heard from Germany — not even from discoverer Hahn. It is not unlikely that the German government, spotting a potentially powerful weapon of war, has imposed military secrecy on all recent German investigations. A large concentration of isotope 235, subjected to neutron bombardment, might conceivably blow up all London or Paris.

It has been impossible, even in this long article, to mention all the thousand aspects of this fascinating phenomenon, or name many of the able contributors to the sum of information amassed since last January. But the fact remains that nuclear fission is the most important scientific discovery of the year, and holds who knows what promise for the future.