KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 



TE AMSTERDAM. 



PROCEEDINGS 



VOLUME XXI 

 N°. 3. 



President: Prof. H. A. LORENTZ. 

 Secretary: Prof. P. Zeeman. 



(Translated from : "Verslag van de gewone vergaderingen der Wis- on 

 Natuurkundige Afdeeling," Vol. XXVI and XXVII). 



CONTENTS. 



W. J. H. MOLL and L. S. OrnsteiN: "Contributions to the study of liquid crystals. III. Melting- and 



congelation-phenomena with para-azoxy-anisol". (Communicated by Prof. W. H. JULIUS), p. 254 

 W. J. H. MOLL and L. S. ORNSTEIN: "Ibid. IV. A thermic Effect of the Magnetic Field'. (Communi- 

 cated by Prof. W. H. JULIUS), p. 259. 

 J. G. VAN DER CORPUT: "The primitive Divisor of x^—l". (Communicated by Prof. J.C. Kluyver), 



p. 262. 

 H. C. BuROER: "On the Evaporation from a Circular Surface of a Liquid". (Communicated by Prof. 



W. H. JULIUS), p. 271. 

 L. BOLK: "On the topographical relations of the Orbits in infantile and adult skulls in man and 



apes", p. 277. 

 JAN DE VRIES: "Null-Systems in the Plane", p. 286. 

 jAN DE VRIES: "Cubic involutions of the first class", p. 291. 

 Jan DE Vries : "Linear Null-Systems in the Plane", p. 302. 



jAN DE VRIES: "Null-Systems determined by two linear congruences of rays", p. 309. 

 E. D. WlERSMA: "The Psychology of Conditions of Confusion", p. 312. 

 J. A. SCHOUTEN: "On the direct analyses of the linear quantities belonging to the rotational group 



in three and four fundamental variables". (Communicated by Prof. J. Cardinaal), p. 327. 

 S.WEBER: "The thermal conductivity of neon". (Communicated by Prof. H. Kamerlinoh OnneS', p. 342. 

 J. E. Verschaffelt: "On the shape of small drops and gas-bubbles". (Communicated by Prof. 



H. Kamerlinoh Onnesi, p, 357. 

 J. E. Verschaffelt: "On the measurement of surface tensions by means of small drops or 



bubbles". (Communicated by Prof. H. Kamerlinoh OnneS), p. 366. 

 A. Smits : "The Phenomenon Electrical Supertension". (Communicated by Prof. P. ZEEMAN), p. 375. 

 A. Smits and C. A. LOBRY DE BRUYN: "On the Periodic Passivity of Iron, 11". (Communicated by 



Prof. P. Zeeman , p. 382). (With one plate). 

 A. Smits and J. M. BiJVOET: "On the System Iron-Oxygen". (Communicated by Prof. S. HOOGE- 



WERFF), p. 386. 

 A. Smits and V. S. F. BerckmanS: "On the System Ether-Chloroform". (Communicated by Prof. S. 



HOOOEWERFF), p. 401. 

 A. J. BijL and N. H. KOLKMEIJER: "Investigation by means of X-rays of the crystal-structure of 



white and grey tin 1". (Communicated by Prof. H. KAMERLINOH ONNES), p. 405. 

 A. WiCHMANN: "On Tin-ore in the Island of Flores", p. 409. 

 H. ZWAARDEMAKER and H. Zeehuisen: "On the Sign of the Electrical Phenomenon and the Influence 



of Lyotrope series observed in this phenomenon", p 417. 

 H. B. A. BOCKWINKEL: "Observations on the development of a function in a series of factorials". 



(Communicated by Prof. H. A. LORENTZi, p 428. 

 TH. DE DONDER: "Le tenseur gravifique". (Communicated by Prof. H. A. LORENTZ', p. 437. 

 J.C. KLUYVER: "On the evaluation of 02n-\-l)", p. 446. 



N. G. W. H. Beeoer: "Ueber die Teilkörper des Kreiskörpers K \e' /". (Erster Teil). (Communi- 

 cated by Prof. W. KAPTEYN), p. 454. 



K (/)". 



17 



Proceedings Royal Acad. Amsterdam. Vol. XXI. 



