546 BELL SYSTEM TECHNICAL JOURNAL 



The Correlation of Distillation Range with the Viscosity of Creosote ^ 

 (Part V of series, "Chemical Studies of Wood Preservation"). C. J. 

 Frosch. The results of viscosity measurements of a series of creosotes 

 distilled from a sinp;le tar are given. It was found that these creosotes 

 are truly viscous solutions, which permits the designation of the data 

 as absolute viscosity. The viscosity-temperature data conform to two 

 equations, one an empirical relationship previously found in an anal- 

 ogous series of crude oils, the other developed from theoretical con- 

 siderations. It is remarkable that in spite of the complex nature of 

 creosote, the viscosity data permit one to regard the material boiling 

 below 355° C. as solvent and the residue above that temperature as 

 solute. This is not true for any other temperature limit customarily 

 used in creosote analysis. 



An Electron Diffraction Camera.'' L. H. Germer. An experimental 

 apparatus is here described for obtaining and photographing electron 

 diffraction patterns from solid substances. It is designed for the 

 study of the crystal structures of thin films and of superficial layers on 

 massive blocks. Electrons from a hot tungsten filament are acceler- 

 ated within an evacuated metal container by a potential difference 

 of 50 or 60 kv. They are stopped down by appropriate slits to form a 

 narrow beam which strikes the material under investigation. Elec- 

 trons scattered by this material form a diffraction pattern character- 

 istic of the crystal structure. This pattern is registered directly upon 

 a photographic plate in the path of the scattered electrons. 



The Motion of a Bar Vibrating in Flexure, Including the Effects of 

 Rotary and Lateral Inertia.^ W. P. Mason. In this paper a complete 

 theoretical solution is given for a bar vibrating in flexure taking ac- 

 count of rotary and lateral inertia. The solution shows that the 

 frequency of a bar free to vibrate on both ends, is asymptotic to the 

 frequency given by the usual solution, neglecting rotary inertia, when 

 the ratio of width to length is small, and approaches the frequency of a 

 bar in longitudinal vibration when the width becomes comparable to 

 the length. The theoretical frequencies have been compared with 

 the published results of Harrison on the frequency of a quartz crystal 

 vibrating in flexure, and have been found to agree within one per cent 

 for a crystal whose width is less than half its length. 



6 Physics, May, 1935. 



' Rev. Sci. Inslruments, May, 1935. 



* Jotcr. Acous. Soc. Amer., April, 1935. 



