CONTENTS 
V 
PAGE 
Preliminary Results on the Color of Nebulae By Frederick H. Scares 553 
Spectrographic Observations of Relative Motions in the Planetary Nebulae 
By W. W. Campbell and J. H. Moore 566 
PHYSICS AND ENGINEERING 
PAQIl 
Experimental Evidence for the Essential Identity of the Selective and Nor- 
mal Photo-Electric Effects By R. A. Millikan and W. H. Souder 19 
Concomitant Changes in Terrestrial Magnesium and Solar Radiation 
By L.A.Bauer 24 
Quantum Relations in Photo-Electric Phenomena By R. A. Millikan 78 
The Emission Quanta of Characteristic X Rays By David L. Webster 90 
The Electromotive Force Produced by the Acceleration of Metals 
By Richard C. Tolman and T. Dale Stewart 189 
The High Frequency Spectrum of Tungsten. . . .By Albert W. Hull and Marion Rice 265 
Dynamical Stability of Aeroplanes By Jerome C. Hunsaker 278 
Theory of an Aeroplane Encountering Gusts By Edwin Bidwell Wilson 294 
Note on the Phosphorescence of Uranyl Salts By Edward L. Nichols 328 
On the Mobilities of Gas Ions in High Electric Fields. .By Leonard B. Loeb 345 
The Light Excitation by Slow Positive and Neutral Particles 
By A. J. Dempster 374 
Channeled Grating Spectra, Obtained in Successive Diffractions 
By C. Barus 378 
A New Method of Measuring the Acceleration of Gravity at Sea 
By Lyman J. Briggs 399 
Marine Meteorology and the General Circulation of the Atmosphere 
By Charles F. Marvin 421 
The Absorption Coefficients of Soft X Rays By CD. Miller 441 
An Attempt to Detect the Mutual Influence of Neighboring Lines in Electric 
Furnace Spectra Showing Anomalous Dispersion By Arthus S. King 461 
Interferometer Methods Based on the Cleavage of a Diffracted Ray 
By C. Barus 475 
The Effect of an Electric Field on the Lines of Lithium and Calcium 
By Janet T. Howell 528 
The Interferences of Spectra Both Reversed and Inverted .. jBy Carl Barus 576 
Path Differences Within Which Spectrum Interferences are Observed. 
By Carl Barus 609 
Non-Reversed Spectra of Restricted Coincidence By Carl Barus 614 
A New Thermometer Scale By Alexander McAdie 670 
An Ionization Manometer By 0. E. Buckley 683 
CHEMISTRY 
PAGE 
A Peculiar Clay from Near the City of Mexico By E. W. Hilgard 8 
Polypeptide-Hydantoins By Treat B. Johnson 69 
The Chemical Activity of the Ions of Hydrochloric Acid Determined by Elec- 
tromotive Force Measurements By James H. Ellis 83 
The Abundance of the Elements in Relation to the Hydrogen-Helium Struc- 
ture OF THE Atoms By William D. Harkins 216 
Change of the Ionization of Salts in Alcoholic Solvents with the Concen- 
tration By Frederick G. Keyes and W. J. Winninghoff 342 
Synthesis of the Base C3H4ON2 Derived from Methyl-Aminomethyl-3,4-Di- 
hydroxyphenylcarbinol By Charles A. RouiUer 464 
