KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 



TE AMSTERDAM. 



PROCEEDINGS 



VOLUME XX 

 N°. 4. 



President: Prof. H. A. LORENTZ. 

 Secretary: Prof. P. Zeeman. 



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

 Natuurkundige Afdeeling." Vol. XXV and XXVI). 



CONTENTS. 



P. ZEEMAN: "Some experiments on gravitation. The ratio of mass to weight for crystals and radio- 

 active substances", p. 542. 



S. DE BOER: "Are contractility and conductivity two separate properties of the skeleton-muscles 

 and the heart?" (Communicated by Prof. G. VAN RijNBERK). p. 554. 



J. Temminck GROLL: "The Influence of Neutral Salts on the Action of Urease". (Communicated 

 by Prof. G. van Rijnberk), p. 559. 



N. H. SlEWERTSZ VAN ReesemA: "The Use of the Thermopile of Dr. W. M. MOLL for Absolute 

 Measurements". (Communicated by Prof. J. BoESEKEN), p. 566. 



A. Smits and J. Gillis : "On Milksugar". II. (Communicated by Prof. S. HOOGEWERFF), 573. 



H. 1. WATERMAN: "Influence of different compounds on the destruction of monosaccharids by 

 sodiumhydroxide and on the inversion of sucrose by hydrochloric acid. III. Constitution-formula 

 of the hydroxybenzoic acids and of sulfanilic acid". (Communicated by Prof. J. BoESEKEN), p. 581. 



A. W. K. DE JONG: "The Structure of Truxillic Acids". (Communicated by Prof. P. VAN ROMBURGH), 

 p. 590. 



L. RUTTEN: "Old Andesites" and "Brecciated Miocene" to the east of Buitenzorg (Java)," (Com- 

 municated by Prof. C. E. A. WiCHMANN), p. 597. 



H. B. A. BOCKWINKEL: "Some Considerations on Complete Transmutation". (Fourth communication). 

 (Communicated by Prof. L. E. J. BROUWER), p. 609. 



A. DE Kleyn and W. Storm van Leeuwen: "Concerning Vestibular Eye-reflexes. I. On the Origin 

 of Caloric Nystagmus." (Communicated by Prof. H. ZWAARDEMAKER), p. 622. 



40 

 Proceedings Royal Acad. Amsterdam. Vol. XX. 



