KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 
TE AMSTERDAM, 
PROCEEDINGS OF THE MEETING 
of Saturday March 31, 1900, 
DC 
(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundige 
Afdeeling van Zaterdag 31 Maart 1900 Dl. VIII). 
Contents: “Determination of the decrease in the vapour tension of solutions by means of the 
determination of the increase in the boiling point”. By Dr. A. Smirs (Communicated 
by Prof. H. W. Bakuuis RoozeBoom) (With one plate), p. 469. — “The formation 
of trisubstituted derivatives from disubstituted derivatives of Benzene”. By Prof. 
A. F. HorLEMAN (Communicated by Prof. C. A. Lopry pe Bruyn), p. 478. — “For- 
ruation and transformation of the double salt of Silvernitrate and Thalliumnitrate”. 
By Dr. C. van Erk (Communicated by Prof. H. W. Baxuvis RoozeBoom), 
p. 480. — “On Orthogonal Comitants”. By Prof. JAN pe Vrigs, p. 485. — “On In- 
digo-fermentation”. By Prof. M. W. BerIJERINCK, p. 495. — “Indican — its hydrolysis 
and the enzyme causing the same”. By J. J. HAZEWINKEL (Communicated by 
Prof. S. Hoocrwerrr), p. 512. — “Contribution to the knowledge of Indican”. 
By Prof. S. HooeewerFF and H. ter MEULEN, p. 520. — “A special case of the 
differential equation of Moree”. By Prof. W. KAPTEYN, p. 525. — “On the Jocus of 
the centre of hyperspherical curvature for the normal curve of n-dimensional space”. 
By Prof. P. H. Scuours, 527. — “Equations in which functions occur for different 
values of the independent variable”. By J.D.van DER Waars Jr. (Communicated by 
Prof. J. D. vAn DER Waars), p. 534. — “The [4-monthly period of the motion of the 
Pole of the’ Earth from determinations of the azimuth of the meridian marks of the 
Leiden Observatory from 1882—1896”. By J. Wrreper (Communicated by Prof. 
H. G. van DE SANDE BAKHUYZEN), p. 546. — “Considerations on Gravitation”. By 
Prof. H. A. Lorentz, p. 559. — “On the power of resistance of the red blood cor- 
puscles”. By Dr. H. J. HAMBURGER, p. 574. — “On the critical isotherm and the 
densities of saturated vapour and liquid in the case of isopentane and carbonic acid”. By 
Dr. J. E. VerscHarrett (Communicated by Prof. H. KAMERLINGH ONNES, p. 574. 
The following papers were read: 
Chemistry. — Prof. H. W. Baxuuts Roozesoom presents an article 
by Dr. A. Smits entitled : “Determination of the decrease in the 
vapour tension of solutions by means of the determination of 
the increase in the boiling point.” 
(Read January 27, 1900.) 
Introduction. 
The peculiar result obtained with the micromanometer ') induced 
me to try and determine the decrease in vapour tension by another 
') Verslag Kon. Academie Jan. 2, 1897, Nov. 27 1897, Sept. 30 1899 and Pro- 
ceedings Sept. 30, 1899. 
34 
Proceedings Royal Acad. Amsterdam. Vol. II. 
