ABSTRACTS 



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PHYSICS. — Resonance and ionization potentials for electrons in cad- 

 mium vapor. P. D. Foote and J. T. Tate. Bur. Stand. Sci. 

 Paper No. 317. Pp. 17. 1918. 

 The object of this investigation has been the determination of the 

 resonance and ionization potentials for electrons in cadmium vapor. 

 Resonance collision of the electron with the atom was observed at 

 3.88 volts and inelastic impact resulting in ionization was observed at 

 8.92 volts. The single hne spectrum of cadmium is X = 3260.17. If 

 we substitute the frequency corresponding to this wave length in the 

 relation hv = eV, where h == 6.56. 10~" erg. sec, e the electronic charge, 

 and V the resonance potential, we obtain V = 3.79 volts, in good agree- 

 ment with the above. On the basis of Bohr's theory the ionization 

 potential should be 8.97, in most excellent agreement with the experi- 

 mentally determined value. P. D. F. 



GEOCHEMISTRY. — The ferrous iron content and magnetic suscept- 

 hility of some artificial and natural oxides of iron. R. B. Sosman and 

 J. C. HosTETTER. Bull. Amer. Inst. Min. Eng. 907-931. June, 

 1917. 

 The percentage of ferrous iron and the relative magnetic suscepti- 

 bility in powder form have been determined on a number of art fie al 

 and natural oxides of iron. Artificial oxides made at 1100*^ and 1200° 

 consist of a solid solution of FesO, in Fe203. Their relative magnetic 

 susceptibility is approximately proportional to their percentage of 

 FeO, from Fe203 over to Fe3 04. The deviations may be partly ac- 

 counted for by the effect of various factors, of which the fineness of 

 grain of the powdered oxide is the most important, especially in the 

 case of the more ferromagnetic members of the series. The colors of 

 the powdered oxides depend both on their chemical composition and 

 on their physical constitution, especially the fineness of grain. 



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