Physics. — “Investigation by means of X-rays of the erystal- 
structure of sodium-chlorate and sodium-bromate”. Communi- 
cation N°. 5 from the Laboratory of Physics and Physical 
Chemistry of the Veterinary College at Utrecht. By N. H. 
Korkmever, J. M. Brvowr and A. Karssen. (Communicated 
on behalf of Prof. W. H. Kersom, Director of the Laboratory, 
by Prof. KAMERLINGH ONNgsS). 
(Communicated at the meeting of May 29, 1920). 
§ 1. Jntroduction. For biological science every deepening of our 
insight into the nature of the chemical bindings of the element 
carbon, so important for the organic world, will be of great value. 
In connexion with the investigation of the structure of the modifications 
of the element carbon itself this point has already been in discussion *). 
Also the close connexion between the atoms of the group CO, 
that has been stated in calcite”) forms an important datum for the 
purpose. Therefore we originally intended to investigate the crystal- 
structure of other carbon-compounds. Sodium-carbonate and sodium- 
bydrocarbonate first came into consideration because of their 
importance for animal life. Considering however that we could 
expect to meet with great difficulties in these investigations especially 
in the calculations as a consequence of the erystal-water resp. the 
monoclinic erystal-system, we first investigated some substances with 
analogous structure, for which these difficulties were not to be 
expected. We chose sodium-chlorate and sodium-bromate both 
erystallizing in the cubic system. We also hoped that these substances 
might give us some indications on the remaining together of the 
atoms of the acid-radical. 
§ 2. Present knowledge on NaClO, and NaBrO,. In P. Grotu’s 
Chemical Crystallography, the erystalforms are described into which 
NaClO, and NabrO, can crystallize under different circumstances. 
When crystallized from solutions in water these substances give at 
1) P. DeBije and P. ScHERRER, Phys. ZS. 19, (1918) p. 476. 
D. Coster, These Proceedings, 28, (1919) p. 391. 
N. H. KoLKMEIJER. Comm. N°. 4; These Proceedings, 28, (1920) p. 767. 
2) W. H. and W. L. Bragg, X-Rays and Crystal-Structure. London, 1918. 
