( 420 ) 



wing figure are obtained according as we are dealing with the 

 modification which is stable, or with that which is metastable 

 below 39°. 



Tenqieraiure. 



As ,. to be foreseen, the velocity of reaction at 39° is the 

 same in both cases ; below this temperature the reaction in the 

 clement containing the stable phase is always the faster (at the 

 same temperature). 



Phys- ^ — ^Diffraction of Ron toen Bays 

 and Dr. C. H. Wind. 



By Prof. H. Haga 



Investigations i) formerly undertaken in the Groningen Laboratory 

 rendered it already clear that, if X rays are due to vibrations of the 

 ether, their wavelength can be but a few Angstrom units. In the course 

 of the further enquiry a phenomenon was observed, indicating traces 

 of real diffraction and tending to give a wavelength of one or two 

 Angstrom units. Now it became possible to perform a new series 

 of ex^^r iments under circumstances more qualified to exhibit diffrac- 

 tio.i. A simple consideration makes it clear that in order to obtain 

 great intensity it is better to use narrow slits than to make the 

 distances great. 



1) C. H. Wind, "On the inÜueuce of the dimensious of the source of light in 

 ditfraction phenomena of Frksnel and on the diffraction of X rays". Kon. Akud. van 

 Wetenschappen. Proceedings, Jixne 1898. 



