KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 
TE AMSTERDAM. 
PROCEEDINGS OF THE MEETING 
of Saturday May 25, 1912. 
DEG = 
President: Prof. H. A. Lorentz. 
Secretary : Prof. P. ZEEMAN. 
(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundige 
Afdeeling van Zaterdag 25 Mei 1912, Dl. XXI). 
COUN, LE ENNE SE 
M. J. van Uven “Homogeneous linear differential equations of order two with given relation 
between two particular integrals’ (5th Communication). (Communicated by Prof. W. 
KAPTErN), p. 2. 
J. W. re Heux: “On some internal unsaturated ethers”. (Communicated by Prof. P. van 
ROMBURGH), p. 19. 
E. H. Biicttyer: “The radioactivity of rubidium and potassium compounds”, IT. (Communicated 
by Prof. A. F. HOLLEMAN), p. 22. 
J. C. Kiuyver: “On a differential equation of ScHAFLr’, p. 27. 
T. van Lonurizen: “Series in the spectra of Tin and Antimony”. (Communicated by Prof. 
P. ZEEMAN), p. 31. (With one plate). 
W. Karrreyn: “New researches upon the centra of the integrals which satisfy differential 
equations of the first order and the first degree” (2nd part), p. 46. 
F. A. H. ScHREINEMAKERS and J. MirikaN: “On a few oxyhaloids”, p. 52. 
L. S. Ornstein: “Accidental deviations of density in mixtures”. (Communicated by Prof. H. A. 
Lorentz}, p. 54. 
G. DE Vrims: “Calculus rationum” (2nd Part). (Communicated by Prof. JAN De Vries), p. 64. 
E. W. Rosenpere: “Contribution to the knowledge of the development of the vertebral column 
of man”, p. 80. 
Pu. Konystamm: “On vapour-pressure lines of binary systems with widely divergent values 
of the vapour-pressures of the components.” (In connection with experiments of Mr. 
Karz) (Communicated by Prof. J. D. vaN DER WAALS), p. 96. 
L. E. J. Brouwer: “On looping coefficients”. (Communicated by Prof. D. J. KorreweG), p. 113. 
Proceedings Royal Acad. Amsterdam, Vol. XV. 
