114 



Tliese values of a show a striking agreeirieiil witli the values 

 obtained in Comni. N". 6rj ') for tlie diameter of the molecule') viz. 



o o 



for oxygen d =: 2.65 A, for nitrogen a =2.98 A. This .snpports the 

 assumption made in Comm. N'. 10 that this diffraction ring should 

 be due to the collaboration of two molecules touching each other. 

 With this wave length we also found for water at the outside 

 of the principal ring a rather uniform blackening, rather sharply 



o 



bounded at <f>^=24°, which corresponds with a distance a = 2.1 A. 



^ 5. For oxygen and nitrogen no diffraction by separate atoms in 

 the molecule. On a well blackened film of oxygen and on that of 

 ai'gon we found indications of a third maximum of blackening, for 

 oxygen at (f =^ 29° and for argon at '/• = 30.5°. We do not pretend 

 the existence of this third maximum to be doubtlessly fixed by these 

 indications. We only draw the following conclusion: If this third 

 maximum really exists, it also does so for argon, so that this 

 maximum cannot be ascribed to the interference of rays that are 

 scattered by the separate atoms in the molecules. 



Though on several films the principal diffraction ring is blackened 

 very intensively, no trace of an interference figure of the separate 

 atoms in the molecule was found in these experiments. Yet with 

 the here used wave length a' ditt'raction ring would have been 



o 



obtained for a distance of the diffracting particles greater than 0,43 A'). 

 For a partial verification of the above we made still an exposition 



») These Proceedings 23, 1920, p. 939. 



-) In fact the smallest distance that is possible between the centres of two 

 molecules in the gas. 



s» According to the discussion of the band spectra the distances of the atom 



o 



nuclei would be for oxygen and nitrogen resp. 0,85 and 1,12 A: A. Eucken, Z S. f. 

 Elektrochemie 26, p. 377, 1920. Comp. W. Lenz, Verh. D. physik. Ges. 21, p. 

 632, 1919. 



