KONIMLIJKE xVKADEMIE VAN WETENSCHAPPEN 

 TE AMSTERDAM. 



PROCEEDINGS OF THE MEETING 

 of Saturday June 24, 1911. 



(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundige 

 Afdeeling van Zaterdag 24 Jnni 1911, Dl. XX). 



oo3vra?EisrTs. 



J. Clay: "On the itiflaence of electric waves upon platinum mirrors. CC')lier('r action). (Com- 

 municated by Trol'. II. Kameulingh Onnks), p. 12C. 



J. SciiMmzKR: "On the oiientution of crystal sections with the help of the traces of two 

 planes and th^ optic extinction". (Communicated by Prof. C. E. A. Wiciimann), p. 128. 

 (With 2 plates). 



S. H. KooRi)KR.s : "A few observations on some new and little known cases of Leguminosae 

 with mechanically irritable leaves", p. ]^2. (With 2 plates). 



L. E. J. Brotiwer: "On the structure of perfect sets of points". (2nd Communication). (Com- 

 municated by Prof. D. J. Korteweg), p. 137. 



.1. A. Barrat": "The surfaces of revolution or quadratic cylinders of non-Euclidean s])ace". 

 (Communicated by Prof. J. Cardinaal), 148. 



W. ÜOCTERS VAN Leevwen and Mrs. J. Docters van Leetwen — Reynvaan: "On the distii- 

 bution of the seeds of certain sjiecies of Dischidia by means of a species of ant: Irido- 

 ;nyimex myrmecodiae Emery". (Communicated by Prof. F. A. F. C. Went), p. 153. 



II. Kamerlingh Onnes and C. A Crommelin: "Isotherm j of monatomic substances and of 

 their binary mixtures. X. The behaviour of argon with respi'ct to the law of correspondiu"- 

 states", p. 1.58. (With 2 plates). XI. "Remarks upon the critical temperature of neon and 

 upon the melting point of oxygen", p. 163. 



W. EiNTiiovEN and J. H. Wieringa: "On diiferent vagus effects upon the heart iiivestigatcd 

 by means of electrocardiography", p. 165. 



N. L. SÖHNGEN: "Thermo-tolerant lijjase". (Communicated by Prof. S. Hoogewerff), p. 1G6. 



A. Smits: "On retrogressive melting-point lines", (2nd Communication). (Communicated by 

 Prof J. D. VAN DER Waals), p. 170. 



A. Smits : "On retrogressive vapour -lines". (First communication). (Communicated by Prof. 

 J. D. VAN DER Waals), p. 177. 



A. Smits and J. P. Treub: "On the coui'se of the PT-lineS for constant concentration in the 

 system eiher — anthraquinone". (Communicated by Prof J. D. van der AVaalsj, p. 183. 



A. Smits and J. P. Treub: "On retrogressive melting-point lines". (Third communication). 

 (Communicated by Prof. J. D. van der Waals), p. 189. 



A. Smits and J. Maarse: "On the system water — phenol". (Communicated by Prof. A. F. 



HOLLEMANy, p. 192. 



F. E. C. ScHEFFER : "On the system hydrogensulphide — water' . (Communicated by Prof. A. F. 

 Holleman), p. 195. 



W. Nernst : "On the inconsistency of my heat theorem and van der Waals' equation at 

 very low temperatures". (Communicated by Prof H. A. Lorentz), p. 201. 



H. Kamerlingh Onnes : "Further experiments with liquid helium", p. 204. 



II. J. ZwiERS : "Preliminary investigation into the motion of the pole of the earth in 1907". 

 (Communicated by Prof. E. F. van de Sande Bakhiiyzen). p. 211. (With one plate). 



M. KoPERBERG: "Notcs OH the SopdCtan- Mountains in the Minahassa". (First part). (Com- 

 municated by Prof. C. E. A. Wichmann), p. 222. 



Erratum, p. 238 



Proceedings Royal Acad Amsterdam. Vol. XIV. 



