121% 
affected by the impulse of the incident rays, in three perpendicular 
directions, and to investigate the consequences of such a supposition 
for the process of the generating of the spots on the photographic plate *). 
In connection with this last supposition, the question could then 
be considered once more, whether the unequal deviations of the law 
of Frantz and WikpeMANN in the principal directions of crystallised 
bismuth and hematite formerly observed,*) were not perhaps to 
be explained in some analogous way? 
Jut let be it as it may, a final explanation of the phenomona 
observed here cannot be given at this moment. In any case it has 
become quite evident, that in the temporarily adopted theory for 
the diffraction-phenomena of RöNtGeN-rays in crystals, a certain factor 
is yet missing, which has the result that the consequences of the 
theory are in agreement with the experimental results only if it is 
applied to isotropous crystals or to those in which the transmission 
of the RÖNTGEN-rays takes place in a direction, in which the erystal 
behaves like an optically isotropous one. 
Only in the last-mentioned cases do the facts appear as full 
illustrations of the theoretical deductions. 
But as long as that theory is unable to explain why the facts 
observed with biaxial crystals do „of coincide with those expected 
by it, the theory can hardly be said to give a final explanation of 
the diffraction-phenomena in crystals at all. 
Systematical experiments with the purpose to elucidate these 
phenomena as well as possible, are momentaneously going on. 
Groningen, Laboratories for Physics and for Inorganic 
March 15, 1915. Chemistry of the University. 
Chemistry. — ‘Researches on Pasteur’s Principle of the Connection 
between Molecular and Physical Dissymmetry.” 1. By Prof. 
Dr. F. M. JarGer. (Communicated by Prof. van RoMBURGH). 
(Communicated in the meeting of March 27, 1915). 
§ 1. It is now matter of common knowledge among scientists 
R\ 
how the classic investigations *) of L. Pasteur, regarding the con- 
nection between the so-called “molecular dissymmetry” of organic 
compounds and their optical behaviour, and especially those investi- 
1) The case of the tartrate has in so far some analogy with that of cordierite, 
that in this case also the optical elasticities in the directions of both the a- and 
h-axes, do not differ very appreciably, in comparison with that in the c-axis. 
2) F. M. Jaeger, These Proc. 15. 27, 89. (1907). 
8) L. Pasteur, Récherches sur ta Dissymmetrie Moléculaire; Legons professées 
devant la Société Chimique de Paris, (1860). 
