KONINKLIJKE AKADEMIE VAN WETENSCHAPPEN 
TE AMSTERDAM. 
PROCEEDINGS OF THE MEETING 
of Saturday February 27, 1909. 
De 
(Translated from: Verslag van de gewone vergadering der Wis- en Natuurkundige 
Afdeeling van Zaterdag 27 Februari 1909, Dl. XVII). 
OMR EE B ARES. 
F. A. H. SCHREINFMAKERS: “The system: Copper sulphate, Copper chloride, Ammonium 
sulphate, Ammonium chloride and Water at 309”, p. 615. 
J. G. SrerswigK: “Contributions to the study of Serumanaphylaxis”. Ist Communication. 
(Communicated by Prof. C. H. H. Spronck), p. 621. 
. alia ; 
Lucien Gopeaux: “The types of bilinear »’ -complexes of M9 in Sp”. (Communicated by 
Prof. P. H. Scmoure), p. 625. 
Hexrp. DE Vries: “The plane curve of order 4 with 2 or 3 cusps and 0 or 1 nodes as a projection 
of the twisted curve of order 4 and of the Ist species”, p. 627. 
Miss WinirreD E. Cowarp: “On Ptilocodium repens, a new gymnoblastic Hydroid epizoic 
on a Pennatulid”. (Communicated by Prof. Max WeBER), p. 635. (With one plate). 
G. C. J. Vosmaer: “On the spinispirae of Spirastrella bistellata (O. 8.) Ldfd.”, p. 642. (With 
one plate). 
J. W. Morr: “Carbon dioxide transport in leaves”, p. 649. 
C. Eyxman: “Investigations on the subject of disinfection”, p. 668. 
Eve. Dusors: “On a long-period variation in the height of the ground-water in the Dunes of 
Holland”. (Communicated by Dr. J. P. van DER STOK), p. 674. 
W. pe Sitrer: “On the periodic solutions of a special case of the problem of four bodies”. 
(Communicated by Dr. E. F. van pe SANDE BAKHUYZEN), p. 682. : 
J. D. van per Waats: “Contribution to the theory of binary mixtures”. XIII, p. 698. 
Chemistry. — “The system: Copper sulphate, Copper chloride, 
Ammonium sulphate, Ammonium chloride and Water at 30°”. 
By Prof. F. A. H. SCHREINEMAKERS. 
(Communicated in the Meeting of January 30, 1909). 
Although the above mentioned five substances take part in the 
construction: of this system only four need be considered as components, 
as between the four salts exists the relation ; 
CuSO, + 2NH,Cl = (NH,),SO, + CuCl,. 
The system constructed from the four salts only ought, therefore, 
to be. looked upon as a ternary one; we will now see first of all 
how we may represent such a system. 
42 
Proceedings Royal Acad. Amsterdam. Vol. XI. 
