ABSTRACTS OF TECHNICAL ARTICLES 399 



sate using a modified differential potentiometric electrode. Acidity 

 data have been obtained for Douglas fir, western hemlock, southern 

 yellow pine, western pine, spruce, redwood, cedar, and oak, and a 

 correlation is attempted between these acidities and the observed 

 corrosive character of the woods. 



Electron Waves.^ C. J. Davisson. This paper is a brief review of 

 the experiments made on the diffraction of electrons by crystal during 

 the first two years following the discovery of this phenomenon, and 

 an indication of the paths along which future experimentation may 

 be expected to proceed. 



Television in Colors by a Beam Scanning Method.'^ Herbert E. Ives 

 and A. L. Johxsrud. It has been recognized ever since the practical 

 achievement of television, and indeed before, that television might 

 be achieved in colors by utilizing the principles used in three-color 

 photography. The requirements in the two cases are very closely 

 parallel. Three-color photography had to wait for its practical 

 achievement, on photographic materials sensitive to all colors of the 

 visible spectrum. The parallel requirement in the case of television is 

 for photoelectric cells similarly color sensitive. The requirements of 

 television as to primary colors to be used for the synthesis of the colored 

 image are relatively more difficult of fulfillment than in the case of 

 color photography because in television we need not merely colored 

 light sources, but light sources which shall be capable of following the 

 variations of the television signal current with high speed. If, how- 

 ever, these two requirements, namely color sensitive photoelectric 

 cells and high speed-colored lights, are met, television in color could 

 conceivably be realized by utilizing any one of a number of devices 

 for analyzing and recombining images which have been successfully 

 applied in three-color photography. 



Air Transport Communication.'" R. L. Jones and F. M. Ryan. 

 The successful operation of an air transportation system depends in 

 no small degree on the communication facilities at its command. 

 Rapid and dependable communication between transport planes in 

 flight and the ground is essential. Two-way radio telephony provides 

 this necessary plane-to-ground contact. 



The design of a radio telephone system for this service requires 

 quantitative knowledge of the transmission conditions encountered in 



^ Jour. The Franklin Inst., Nov. 1929. 

 * Jour. Opt. Soc. of Amer., Jan. 1930. 

 'Jour. A. /.£.£., Jan. 1930. 



