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In the atomic symposium, some differences of opinion between the physicist and the chemist came to light. Said Prof. Millikan in substance:
All scientists agree upon an atom which has a very minute, positively charged nucleus, neutralized by a number of negative electrons which surround it. The nucleus has always a definite number of positive charges upon it, varying from one (hydrogen) to 92 (uranium). Outside the nucleus are the negative electrons, varying in number in the same way. The outermost layer of these are the valence electrons, which mingle with those of other atoms in the process of combination. So far as physical science has gone, there have appeared but two fundamental entities, positive and negative electrons—the building stones of the universe.
Electrons in the outer circles may be radiated out by falling from a higher potential energy to a lower, and the frequency of radiation is proportional to the energy loss in the process. This is the Einstein-Bohr law of radiation, which has been amply verified in the past five years. As to what the electrons are doing when they are not radiating, chemists and physicists on the whole hold divergent views. The chemist believes the electrons are at rest (what I call "the loafer theory"), but the physicist believes they are rotating in orbits at enormous speed. The chemist argues that such activity would soon dissipate all their energy, which is unanswerable if the electromagnetic laws are assumed to be valid even in the structure of atoms. But this assumption is gratuitous. The orbit theory has now been substantiated by several successful quantitative tests, but the original Bohr theory of the shape of the orbits will have to be modified by spectroscopic analysis.
Dr. Lewis, recent winner of the Willard Gibbs medal in physical chemistry, upheld the magnetic nature of the electrons, which, like any other current of electricity, become magnets when moving in circles. They travel in pairs, 180 degrees apart, neutralizing each other, and thus holding together all chemical compounds. Instead of the Bohr atom with its positive nucleus, Dr. Lewis claimed that the electrons, though having orbits, do not revolve around the "kernel" of the atom. No one has been able to work out a satisfactory path for these paired electronic orbits, but that fact does not bother the chemists so much as the physicists. Instead of a general orbit for all, like the rings of Saturn, each pair of electrons probably has an independent orbit.
Dr. Lewis, optimistic about the future of atomic investigation, pointed out a progressive convergence of the various theories. The differences between physicists and chemists, he said, will disappear in less than a year. President Baekeland, when the two speakers had finished, told the delegates: "Now you have heard them both. You can decide for yourself which one is the high church theory."
Other high lights in the program:
¶ Dr. Richard B. Moore again championed helium as an aeronautic gas. The Dixmude, ZR-2, and Roma disasters would not have occurred, if it had been used, he said. Within a year or two, the cost of production will be practically as cheap as for hydrogen.
¶ The three great food groups—proteins, fats and carbohydrates—can theoretically all be made synthetically, said Dr. Carl L. Alsberg, former chief of the Bureau of Chemistry, now 'director of the