KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 
TE AMSTERDAM. 
PROCEEDINGS OF THE MEETING 
of Friday April 23, 1909. 
ICG 
(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundige 
Afdeeling van Vrijdag 23 April 1909, Dl. XVII). 
GO MN PE NaS: 
C. Easton: “On Lockyer’s 35-year period in the solar activity”. (Communicated by Dr. 
J. P. van DER STOK), p. 842. (With one plate). 
Z. P. Bouman: “A family of differential equations of the first order”. (Communicated by 
Prof. JAN DE VRIES), p. 847. 
L. E. J. Brouwer: “On continuous vector distributions on surfaces”. (Communicated by 
Prof. D. J. Korrewee), p. 850. 
J. G. SreeswiJK: “Contributions to the study of Serumanaphylaxis”. 3nd Communication. 
(Communicated by Prof. C. H. H. Spronck), p. 859. 
J. P. Darton: “Researches on the Joure-Kervin effect, especially at low temperatures. 
I. Calculations for hydrogen”, p. 863. (With one plate). — IL. The Jourr-Kervin effect for 
air at 0° C. and at pressures up to 42 atmospheres”, p. 874. (With 2 plates). (Communicated 
by Prof. H. KAMERLINGH ONNES). 
H. KAMERLINGH Onnes: “Methods and apparatus used in the Cryogenic Laboratory. XV. 
An apparatus for the purification of gaseous hydrogen by means of liquid hydrogen”. p. 883. 
(With one plate). 
J. H. Merrpure: “On the motion of a metal wire through a piece of ice”. IT, (Communicated 
by Prof. H. A. Lorentz), p. 886. 
J. D. van per Waars: “Contribution to the theory of binary mixtures”, XV. Splitting up of 
the spinodal line”, p. 890. 
Pu. Konunstamm: “On the course of the isobars for binary systems”. III (Communicated by 
Prof. J. D. vAN DER Waats), p. 906. 
Pa. KonnstamM and J,. Cur. Reepers: “On the phenomena of condensation for mixtures 
of carbonic acid and urethane, in connection with double retrograde condensation”. (Commu 
nicated by Prof. J. D. var DER Waats), p. 913. 
57 
Proceedings Royal Acad. Amsterdam. Vol, XI, 
