XXVI GOoNTEN &S5 
Physics. H. C. BurGer and P. H. van Cittert: “Measurements on the 
intensity of spectrum lines by the aid of the echelon.” 790. 
— Miss Rassa RriwriN: “Photographic absorption- and extinction- 
measurements. Contributions to the study of liquid crystals. V. 
Extinction-measurements.” 807. 
— G. KrurKow: “On the determination of quanta-conditions by means 
of adiabatic invariants.” 826. 
— Arpa. DEUMENS: “Extinction by a blackened photographic plate as 
function of wavelength, quantity of silver, and size of the grains.” 848. 
— 1. K. A. WERTHEIM SALOMONSON: “The mechanism of the automatic 
current interrupter.” 869. 
— J.J. VAN LAAR: “On the equation of state for arbitrary temperatures 
and volumes. Analogy with PLANCK’s formula.” II. 887. 
— W. H. Keesom: “The quadrupole moments of the oxygen and nitrogen 
molecules.” 939. | 
— W. H. Keesom: “The cohesion forces in the theory of VAN DER 
Waats.” 943. 
— P. EHRENFEST: “Note on the paramagnetism of solids.” 989. 
— H. A. Kramers: “On the application of EINSTEIN’s theory of gravi- 
tation to a stationary field of gravitation.” 1052. 
— J. M. BurcGers: “Stationary streaming caused by a body in a fluid 
with friction.” 1082. 
— J. A. SCHOUTEN: “On geodesic precession.” 1108. 
— W. H. Jurrius: “Mutual influence of neighbouring Fraunhofer lines.” 1113. 
— W. H. Kessom: “On the deviations of liquid oxygen from the law of 
Curie.” 1127. 
— E. Martuias, C. A. CROMMELIN and H. KAMERLINGH ONNEs: “The 
rectilinear diameter of hydrogen.” 1175. | 
— H. KAMERLINGH ONNEs and C. A. CROMMELIN : “Methods and appa- 
ratus used in the cryogenic laboratory. XVIII. Improved form of a 
hydrogen vapour cryostat for temperatures between —217° C. and 
—253° C. 1185. 
— P. S. Epstein: “On the principles of the theory of quanta.” 1193. 
— J. M. BiyvorT and A. KarssEN: “Research by means of Röntgen-rays 
on the structure of the crystals of lithium and some of its compounds 
with light elements.” I. 1365. 
— P. ZEEMAN, W. DE Groot, Miss A. SNETHLAGE and G. C. DIBBETz: 
“The propagation of light in moving, transparent, solid substances. III. 
Measurements on the Fizeau-effect in flint glass.” 1402. 
— H. Zanstra: “Motion relativated by means of a hypothesis of A. 
FörrL.” 1412. 
