KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 



TE AMSTERDAM. 



PROCEEDINGS 



VOLUME XXVI 

 N°^ 1 and 2. 



President: Prof. F. A. F. C. WENT. 

 Secretary : Prof. L. BOLK. 



(Translated from : "Verslag van da gewone vergaderingen dor Wis- en 

 Natuurkundige Afdeeling," Vols. XXXI and XXXII). 



CONTENTS. 



B. L. VAN DER Waerden: "Ueber das Komitantensystem zweier und dreier ternarer quadratischer 



Formen". (Communicated by Prof. L. E. J. BROUWER), p. 2. 

 EJNAR Hertzsprung: "On the magnitude equation of OSTHOFF's estimates of star-coulours", p. 12. 

 Chr van Gelderen : „On tlie development of the shoulder-girdle and episternum in Reptiles'. 



(Communicated by Prof. L. BOLK), p. 15. 

 P. H. HERMANS: "Provisional Communication on Boric Acid Compounds of some Organic Substances 



containing more than one Hydroxyl-Group. Boron as a Pentavalent Element". (Communicated 



by Prof. J. BÖESEKEN), p. 32. 

 H. R. Kruvt and W. A. N. EOOINK: "The Electro-viscous Effect in Rubbersol", p. 43. 

 ). P. KUENENf, T. VERSCHOYLE and A, Th. VAN URK: "Isotherms of di-atomic substances and their 



binary mixtures. XX. The critical curve of oxygen-nitrogen mixtures, the critical phenomena and 



some isotherms of two mixtures with SWYu and TS"/» by volume of oxygen in the neighbourhood 



of the critical point". (Communicated by Prof. H. Kamerlinoh Onnes), p. 49. 

 Kyozo Kudo: "Contributions to the knowledge of the brain of bony fishes". (Communicated by 



Dr. C. U. Ariëns Kappers), p. 65. 

 H. J. Backer and J. H. DE BOER: "n.a-Sulfobutyric acid and its optically active components". 



(Communicated by Prof. F. M. Jaeger), p. 79. 

 H. J. Backer: "The second dissociation constant of sulphoacetic and a-sulphopropionic acids" 



(Communicated by Prof. F. M. JAEGER), p. 83. 

 H. BOSCHMA: "Experimental Budding in Fungia fungites". (Communicated by Prof. C. PH. Sluiter) 



p. 88. (With one plate). 

 J. BÖESEKEN: "The Valency of Boron", p. 97. 

 W. H. Keesom and J. DE Smedt: "On the diffraction of Röntgen-rays in liquids" II. (Communicated 



by Prof H. KAMERLINQH Onnes), p. 112. 

 P. C. FLU: "On the Bacteriophage and the Self-purification of Water", p. 116. 



Proceedings Royal Acad. Amsterdam. Vol. XXVI. 



