KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 
TE AMSTERDAM, 
PROCEEDENGS OF THE MEETING 
of Saturday May 27th, 1899, 
ei 
(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundigo 
Afdeeling van Zaterdag 27 Mei 1899 Dl. VIII). 
Contents: “On the system: water, phenol, acetone.” By Dr. F. A. H. SCHREINEMAKERS (Com- 
municated by Prof. J. M. vaN BEMMELEN), p. 1. — “On the nitration of benzoic acid 
and its methylic and e:hylic salts.” By Pret. A. F. HorLEMAN (Communicated by Prof. C. A. 
LoBry DE Bruyy). p. 4. — “The system of Sirius according to the latest observations.” 
By Mr. H. J. Zwiers (Communicated by Prof. H. G. VAN DR SANDE BAKHUYZEN). 
p. 6. (With one plate). — “Measurements on the magnetic rotation of the plane of 
polarisation in oxygen at different pressures.” By Dr. L. H. SIERTSEMA (Communicated 
by Prof. H. KAMERLINGH ONNES). p. 19. 
The following papers were read: 
Chemistry. — “On the system: water, phenol, acetone.” By Dr. 
F. A. H. SCHREINEMAKERS. (Communicated by Prof. J. M. 
VAN BEMMELEN.) . 
Two cases may, in general, be distinguished in which plaitpoints 
appear or disappear on the ¢-surface (by the ¢-surface without further 
qualification, is meant, both here and in what follows, that area 
of the ¢-surface which relates to the liquid state). 
1. The plaitpoint appears at the margin of the ¢-surface. 
2. The plaitpoint appears, on the ¢-surface itself and not at its 
margin. 
Mr. SCHREINEMAKERS has already found experimentally various 
examples ef the first case; for example, in the equilibria between 
water, succinonitrile and sodium chloride salt or ethylic-aleohol and 
1 
Proceedings Royal Acad, Amsterdam, Vol. II. 
