653 
From the values found for the parameters it is evident that each 
time three oxygen-particles are lying close round each halogen- 
particle; the plane of the three oxygen-particles perpendicular to a 
ternary axis contains, approximately at least, the halogen-particle. 
The distance between the centres of a halogen- and one of those 
neighbouring oxygen-particles is about + of the parameter of the 
lattice !). The situation of the groups Nat and CIO, resp. BrO,— can 
be found from the NaCl-model by diminishing the distance between 
the opposite ions all by about # of their value. 
Finally we wish to express our indebtedness to Prof. Kersom for 
his kindness to place his laboratory at our disposal for this investi- 
gation and for his great interest and help. 
1) (Note, added during translation). Quantitatively these values are not in accord- 
ance with the data of Brage (Phil. Mag. (6) 40 (1920) p. 169. The distances of 
the centres of an O- and a Cl-atom or a Br-atom, which, according to Brace’s 
data ought to be 1.70.10—-8 and 1.84.10—8 respectively are found by us as 
0.910.10-8 and 0.937.10—8 respectively This discrepancy is not astonishing, 
seeing 1 that in note 1) of the preceding page some reserve is made about the 
accuracy of the parameters for the O-particles; 2 that Braaa expects a shortening 
of the distance in discussion in radicals in which there is strong binding. 
We thought it desirable however, to investigate this point nearer, with this 
aim new photos will be taken and discussed by two of us (B. and Kaj. The 
intensities of the lines with the smallest radii especially, lying in a dark part of 
the film, can perhaps be determined more accurately. when an antikathode is 
used, which gives a larger wavelength and when the radius of the camera is 
enlarged. 
42 
Proceedings Royal Acad. Amsterdam. Vol. XXIII. 
