Cascading Electrons

Practical scientists who were able to attend the winter meeting of the American Institute of Electrical Engineers at Manhattan last week edged forward on their seats when rumpled-haired Dr. William David Coolidge began to explain his further experiments with cathode rays. Dr. Coolidge, assistant director of the General Electric Co.'s research laboratories, had just received the Institute's Edison Medal for his "contributions to the incandescent electric lighting and x-ray arts" by his development of ductile tungsten for bulb filaments and x-ray targets. At the same ceremony John Joseph Carty of the American Telephone & Telegraph Co. had received the John Fritz Medal for his "development of research in the telephone art."

Dr. Coolidge's latest experiments have been with the fundamentals of matter. He makes electricity behave like radium. He knocks molecules into atoms, atoms into electrons. He changes the nature of things --with electricity.

Cathode Rays. Little more than a generation ago the British physicist Sir William Crookes sealed the ends of two wines in a glass tube and in the tube created a vacuum. Then he shunted a current of electricity into the wires. The current sent a stream of electrons speeding from one of the wires, the cathode. They were cathode rays and they behaved in some ways like radium, soon after to be discovered by the Curies. They made the vacuum tube glow with-brilliant fluorescence. If a piece of metal were sealed in the tube, in the path of the rays, the metal became very hot. It also cast a sharp shadow on the wall of the tube. The Crookes tube, refined in mechanism, is the common x-ray tube of today, useful to physicists, metallurgists, biologists, doctors, dentists. (In 1895 the German physicist Wilhelm Konrad Rontgen discovered the penetrating powers of the rays.)

Coolidge Tube. In x-ray tubes the electrons popping from the cathode are imprisoned within the tubes. How to get them outside became a problem for scientists. Philip Lenard, Nobel prizewinner for 1905 and now professor at the University of Heidelberg, solved it by placing a thin aluminum "window," one eighth of an inch in diameter, at one end of a tube. Electrons passed through it, but feebly. He used only 30,000 volts of electricity.

Dr. Coolidge, working with able assistants at the Schenectady research laboratories of General Electric, two years ago succeeded more magnificently. For his window he used a sheet of nickel 1/2000 of an inch thin. (Human hair varies between 6/1000 and 126/10,000 of an inch in diameter.) And he used 350,000 volts of current. Electrons hurtled through the nickel foil, speeding about 150,000 miles a second (four-fifths the speed of light). As beta and gamma rays, similar to the offshoots from radium, they turned acetylene gas into a yellow powder such as scientists never before had seen. They made minerals fluoresce, killed bacteria and insects, burned a rabbit's ears (TIME, Nov. 1, 1926).

Tandem Tubes. To get gamma rays to rush as fast from his tube as they do from radium, Dr. Coolidge would need about 2,000,000 volts of electricity. To get beta rays as penetrating as those from radium, he would need 3,000,000 volts. If he could create such voltages and if he could direct them properly, he would be, according to Philosopher Henri Bergson, at the heart of the world. Dr. Coolidge has succeeded in using 900,000 volts effectively. How he worked, he described to the engineers at Manhattan last week after receiving his latest medal.

He joined three of his vacuum tubes in tandem and in the connecting necks placed hollow metal cylinders. From a tungsten filament cathode in the first tube, 300,000 volts of electricity shot cathode rays into the first metal cylinder, which functioned as anode to the first and cathode to the second. There 300,000 more volts kicked the speeding electrons into the next similarly acting cylinder, where 300,000 more volts gave a final kick. The rays cascaded out of the apparatus at 175,000 miles per second--almost as fast as light, 350,000 times faster than a rifle bullet. Dr. Coolidge watched them, hiding within a lead-lined, lead-paned booth so that he might not be injured by the incalculable effects of his experiments.

Utility. These artificial radium rays left the tube in quantities naturally obtainable from a ton of radium. That much radium has not yet been produced. If it existed, at present prices it would be worth $56,000,000,000. The uses of so much energy are unfortellable.

The penetrating gamma rays might be deflected from a metal target, as in simple x-ray tubes, and reveal unknown properties of bodies.

The beta rays (electrons, negatively charged particles) rat-tat-tat-ing against the atoms of elements might conceivably change those elements into new and precious forms. Mercury might yet become gold, as alchemists dreamed. Theoretically the procedure is simple. An atom of mercury contains at its centre, 198 protons (positively charged particles) and 118 electrons. Around that nucleus swirl 80 more electrons. These complete the mercury balance of 198 electrons against 198 protons. An atom of gold contains 197 protons and 118 electrons in its nucleus and 79 more electrons shooting around them. If it becomes possible for the beta particles from Dr. Coolidge's tandem tubes to blast a proton from the nucleus of a mercury atom and if an unrestrained electron flies away from the mercury orbit, then mercury becomes gold.