614 Molecular Dimensions of Ammonia, Pliosphine, Sf Arsine- 



collision areas and atomic diameters, as indicated in 

 Table VII. 



Table VII. 

 All areas are in cm. 2 x 10" 13 , and diameters in cm. X 10~ 8 . 



Gas. 



Old values. Corrected values. 



C. 



A=7T<7 2 . 



2(7. C. 



A.=iz<jK 



1 



(7. 



2-30 

 2-87 

 3-10 

 3-41 



i 



Neon 



56 

 162 



188 

 252 



0-435 

 0-648 

 0-797 

 0-970 



2 35 69 

 2-87 162 

 3-19 212 

 3-51 283 



0-417 

 0-648 

 0-757 

 0-915 



Argon 



Krypton 



Xenon 



The corrected values so obtained for neon, argon, and 

 krypton have been inserted in Table VI. for comparison 

 with the corresponding gases ammonia, phospbine, and 

 arsine, and the last column in tbat table gives the difference 

 between the values in columns (2) and (4). 



It will be seen that the increases in passing from neon to 

 ammonia, argon to phosphine, and krypton to arsine, are 

 approximately equal, and according to the Lewis- Langiimir 

 theory are to be attributed to the effect of the addition of the 

 three nuclei of those hydrogen atoms which have attached 

 themselves to the nitrogen, phosphorus, and arsenic atoms, 

 respectively, to complete the electron configuration appro- 

 priate to the corresponding inert atom. This is an interesting- 

 result, but it will not be possible to say what degree of 

 support it may lend to the Lewis-Langmuir theory until the 

 distances between the hydrogen nuclei and those of the 

 elements to which they are attached, i. e. nitrogen, phos- 

 phorus, and arsenic, respectively, become known. Experi- 

 ments are in progress for the purpose of examining other 

 gaseous hydrides from thia point of view, and it is expected 

 tbat the results will be published shortly. 



Imperial Colleore of Science and Technology, 

 17th June, 1921. 



