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SCIENCE

12231
6

NEW SERIES. VOLUME LXIV

JULY-DECEMBER, 1926

NEW YORK
THE SCIENCE PRESS

1926

THE SCIENCE PRESS

PRINTING COMPANY LANCASTER, PA.

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Lancaster, Pa. Garrison, N. Y. New York City: Grand Central Terminal. Annual Subscription, $6.00. Single Copies, 15 Cts.

SCIENCE is the official organ of the American Association for the Advancement of Science. Information regarding membership in the Association may be secured from the office of the permanent secretary, in the Smithsonian Institution Building, Washington, D. C.

Entered as second-class matter July 18, 1928, at the Post Office at Lancaster, Pa., under the Act of March 8, 1879.

THE IONIZATION OF GASES AS
A TYPE OF CHEMICAL
ACTIVATION1

"CHEMICAL activation" is a generic term embracing the various processes by which substances are brought into a state of chemical activity. The use of this term is by no means new, but the intense investigation of the subject during the past ten years may be regarded as a recognition of the incompleteness of our knowledge of one of the fundamentals of chemistry.

We are by now fully aware of what earlier was not so apparent that the commonest and most useful type of activation, that of temperature influence, is the most complex of all in point of theory. The numerous attempts to relate temperature coefficient of velocity of reaction through the internal radiation theory, or to explain it in other ways have at best left the subject in an unsatisfactory condition. However, it is not my purpose to discuss these attempts but to take up one of the simpler types of activation.

Of the non-thermal modes of activation, besides contact catalysis we have the various radiant forms, including photochemical rays and the different kinds of corpuscular streams which may be made to act on gaseous systems. The primary activated products of these various radiative agencies may be classified as free atoms, excited atoms or molecules, and ionized atoms or molecules. In ionization an electron is entirely removed from an atom or molecule, thus producing negative and positive charges which are capable of quantitative measurement by electrical discharge methods. Uncharged atoms do not have any properties by which their concentrations can be so definitely determined. For this reason, if we apply a source of energy so as to produce a known quantity of ions in a given system, in which the chemical reaction produced can also be measured, we are in a position to establish more accurate and definite relations between primary activation and resulting chemical action than has been done in any other type of activation.

In electrolysis, the ratio of discharge of ions at the electrode to chemical action produced is expressed in Faraday's law. In an ionized gaseous system where no field is imposed and hence no current flow

1 Address at the presentation of the W. H. Nichols Medal by the New York Section of the American Chemical Society, March 5, 1926.

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