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TOL. 939 No. 240884

SCIENCE

FRIDAY, FEBRuARY 21, 1941

Ions in Gases: PROFESSOR JOHN ZELENY .............................. 167

Botanical Research by Unfashionable Technics: PRo-FESSORNEILE. STEVENS .............. ............................. 172

Scientific Events:The Research Section of the Rochester Academy ofScience; Conference of Radio Engineers at theOhio State University; Symposia at the St. LouisMeeting of the American Chemical Society; Sym-posium at Union College; Nominations of Officersof the American Institute of Electrical Engineers;Appointment of Dr. James Bryant Conant as Headof a Scientific Mission; Recent Deaths .............................. 176

ScientificNotes and News ............ ............................... 179

Special Articles:On Lubimenko Extracts of Chlorophyll-Protein:DR. M. L. ANSON. The H-ion Concentration andthe Origin of the Heart Beat: DR. C. R. SPEALMAN.Susceptibility to Disease in Relation to Plant Nutri-tion: DR. WALTER THOMAS and DR. WARREN B.

MACK ............................... .. 186

Scientific Apparatus and Laboratory Methods:Histological Sectioning of Hard Tissues by a NewTechnique: ALEXANDER RANDALL, IV and PRo-FESSOR ALAN W. C. MENZIES. The Staining ofAcid-fast Tubercle Bacteria: DR. OSCAR W. RICH-

ARDS ............ 189

Science News 6

Discussion:An Important Factor in Evolution: DR. MELVILLEH. HATCH. Linneus on the Natural History ofMan: FRANCIS H. ALLEN. The Soybean in China:PROFESSOR L. CARRINGTON GOODRICH. Our Sci-ence Meetings Again: DR. WILLIAM SEIFRIZ. ThePresentation of Scientific Papers: PROFESSOR J.VAN OVERBEEK ... 182

Scientific Books:The Design of High Pressure Plant: PROFESSOR P.W. BRIDGMAN. Abstract Algebra: PROFESSOR GAR-

RETT BIRKHOFF .................. 185

SCIENCE: A Weekly Journal devoted to the Advance-ment of Science, edited by J. McKEEN CATTELL and pub-lished every Friday by

THE SCIENCE PRESSLancaster, 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 Associa-

tion for the Advancement of Science. Information regard-ing membership in the Association may be secured fromthe office of the permanent secretary in the SmithsonianInstitution Building, Washington, D. C.

IONS IN GASES'By Professor JOHN ZELENY

YALE UNIVERSITY

The problem of size and that of mass, which isusually connected with it, has been one of great per-plexity. This problem presented itself at the veryoutset of the study of these ions, and has remainedwith us ever since.

Forty-four years have passed since Thomson andRutherford2 adopted the ionization theory to explainthe conductivity imparted to gases by x-rays. At thetime, the electron had not been isolated, and the processof ionization of a diatomic molecule was regarded as

consisting in the pulling apart of its two atoms.However, when Thomson and Rutherford obtained a

rough estimate of the speeds with which the ionsmigrate in an electric field, they found that the mobil-ity was much smaller than an ion of atomic size shouldhave according to the kinetic theory of gases.

2 J. J. Thomson and E. Rutherford, Phil. Mag., 42: 392,1896.

WHAT I propose to do in this paper is to outlinebriefly some of the difficulties which have been met inour attempts to get a better understanding of gaseous

ions, and to indicate the present state of our knowledgeabout these ions. And then lastly, I shall go somewhatafield to say something about the theories that havebeen proposed to account for lightning.To begin, then, what is there that we should like to

know about ions in gases? We should like to knowtheir mass, size, composition and structure. We shouldlike to know the amount of charge that each carries.And we should like to know how they differ and whatpart each plays in the various electrical discharges.For obvious reasons, I shall not attempt to discuss allthese various aspects of the subject.

1 Address of the retiring president of the AmericanPhysical Society given in Philadelphia, December 27,1940.

VOL. 93 No. 2408

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