KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 



TE AMSTERDAM. 



PROCEEDINGS 



VOLUME XXI 

 N°. 4. 



President: Prof. H. A. LORENTZ. 

 Secretary: Prof. P. Zeeman. 



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

 Natuurkundige Afdeeling," Vol. XXVI and XXVII). 



CONTENTS. 



C. SCHOUTE, F. A. VAN Heyst and N. E. Qroeneveld MEIJER: "An instrument to be used by the 

 pilot of an aeroplane to measure the vertical velocity of the machine", (communicated by 

 Dr. VAN DER STOK), p. 468. 

 G. GRIJNS: "Is there any Relation between the Capacity of Odorous Substances of Absorbing 



Radiant Heat and their Smell-Intensity?" p. 476. 

 F. A. P. C. WENT: "On the course of the formation of diastase by Aspergillus niger", p. 479. 

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



white and grey tin II. The structure of white tin, p. 494. Ibid III. The structure of grey tin." 



(Communicated by Prof. H. KAMERLINGH Onnes), p 501. 

 A. D. FOKKER: "On the equivalent of parallel translation in non-Euclidean space and on Riemann's 



measure of curvature". (Communicated by Prof. H. A. LORENTZi, p. 505. 

 W. J. A. SCHOUTEN: "The Distribution of the absolute Magnitudes among the Stars in and about 



the Milky Way". iFirst Communication). (Communicated by Prof. J. C. KAPTEVN), p. 518. 

 J. A. SCHOUTEN: "On the arising of a precession-motion owing to the non-euclidian linear element 



of the space in the vicinity of the sun". (With Addendum by Prof. W. DE Sitterk 'Communi- 

 cated by Prof. LoRENTZi, p. 533. 

 Miss. M. A. VAN HERWERDEN: "Effects of the Rays of Radium on the Oogenesis of Daphnia 



pulex". (Communicated by Prof. C. A. PEKELHARING), p. 540. 

 H. J. HAMBURGER and R. BRINKMAN: "The conduct of the kidneys towards some isomeric sugars". 



(Glucose, Fructose, Galactose. Mannose and Saccharose, Maltose, Lactose), p. 548. 

 A. Smits and J. M. Bijvoet: "On the Significance of the Volta-Effect in Measurements of Electro- 

 motive Equilibria". (Communicated by Prof. P. ZEEMAN), p. 562. 

 J. F. VAN Bemmelen: "Androgenic origin of Horns and Antlers", p. 570. 

 A. W. K. DE JONG: "On the estimation of the geraniol content of citronella oil". (Communicated by 



Prof. VAN ROMBURGH), p. 576. 

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



(Communicated by Prof. H. A. LORENTZ), p. 582. 

 W. H. Keesom and Mrs. C. NORDSTRÖM-VAN LEEUWEN: "Deduction of the third virial coefficient 



for material points (eventually for rigid spheres), which exert central forces on each other". 



(Communicated by Prof. H. KAMERLINGH Onnes>, p. 593. 

 W. H Keesom and Mrs. C. NORDSTRöm-van Leeuwen: "Development of the third virial coefficient 



for material points (eventually rigid spheres», which exert central attracting forces on each 



other proportional with r "^ or r ." (Communicated by Prof. H. KAMERLINGH OnneSi, p. 602. 

 J. A. SCHOUTEN: "On the number of degrees of freedom of the geodetically moving system and 



the enclosing euclidian space with the least possible number of dimensions". (Communicated 



by Prof. J. CardinaaL), p. 607. 

 Felix Klein: "Bemerkungen iiber die Beziehungen des de SiTTER'schen Koordinatensystems B zu 



der allgemeinen Welt konstanter positiver Kriimmung", p. 614. 

 O. PoSTMA: "On friction in connexion with Brownian movement". Communicated by Prof. H. A. 



LORENTZ), p 616. 



31 

 Proceedings Royal Acad. Amsterdam. Vol. XXI. 



