ABSTRACTS OF TECHNICAL ARTICLES 479 



becomes and remains capable of conducting electricity, and acquires 

 and retains other interesting qualities. Such are: "ionization," the 

 detachment of electrons from atoms and molecules by electron-impact, 

 light, impact of positive ions, and other agencies; "excitation," the 

 transfer of atoms and molecules, by these same agencies, into abnormal 

 or excited states in which they possess extra energy and various peculiar 

 powers — the return of excited atoms to their normal condition, with 

 emission of light or with other modes of energy-surrender; "inter- 

 ception," the deflection and slowing-down of electrons and positive 

 ions by collisions with molecules and atoms. After the four chapters 

 devoted to these elementary processes, come four concerned with the 

 drift and diffusion of electrons and more massive ions through dense 

 gases, and with allied topics: material often classified under such names 

 as "mobility," "diffusion," "recombination" and "capture of elec- 

 trons." The following chapter is assigned to the drifting of ions 

 through dense gases under fields so strong that these ions themselves 

 produce extra ionization, and to the phenomena of "breakdown" 

 which is sometimes sparkover, sometimes the establishment of a dis- 

 charge such as a glow or an arc. After a chapter on the distortion of 

 electric fields by space-charge, essential to what follows, there comes 

 a treatment of the properties of highly ionized and luminous gases 

 such as the mercury-vapor arc exemplifies, and of space-charge sheaths, 

 as clarified of recent years by newly developed probe-methods. The 

 final chapters are descriptions of the important types of discharge 

 known as self-sustaining glow and self-sustaining arc. The book is 

 thus so arranged as to proceed from the fundamental atomic phe- 

 nomena, through the intermediate topics of drift and diffusion of ions 

 through gases, to the most intricate discharges. In the later parts, 

 especial attention has been paid to such phenomena as have been 

 made at least partially intelligible in terms of the processes described 

 in the earlier; nevertheless, those which have not been interpreted 

 are given due place and emphasis. 



Electrical Phenomena in Gases is Dr. Darrow's second book. Intro- 

 duction to Contemporary Physics was published by D. Van Nostrand 

 Company in 1926. 



Application of Quartz Plates to Radio Transmitters.^ O. M. Hov- 

 GAARD. This paper discusses the disturbing elements encountered in 

 the application of quartz plates to broadcast and aircraft radio trans- 

 mitters. A general procedure for minimizing such effects is considered 

 from a circuit standpoint as well as in the light of practical experience. 



^Proc. I. R. E., May, 1932. 



