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TRANSACTIONS OP SECTION A. 



2. On the Atomic Structure of the Elements, with Tfieoretical Determinations 

 of their Atomic Weights. By J. W. Nicholson, M.A., D.Sc. 



This paper dealt with the inner structure of the chemical atoms, and gave a 

 selected portion of a more general theory. This theory is based on a conception 

 of positive electricity as existing in volume distributions of uniform density. 

 The four most elementary atoms, representing the most primitive types of 

 matter, have respectively two, three, four, and five electrons in the atom, with 

 the quantity of positive electricity required to render the atom electrically 

 neutral. 



The inertia of an atom is regarded as the sum of the inertias of its positive 

 and negative charges, the latter being of a lower order of magnitude. For a 

 single charge of either sign, the inertia is proportional to radius charge. 



The elementary atoms or ' protyles ' above are identified with four elementary 

 substances. The atom with two electrons, lighter than that of Hydrogen, is 

 believed to be an inert gas, Coronium, found in the solar corona. That with 

 three electrons is Hydrogen. The atom with four is called Nebulium, the main 

 basis of the simpler nebulae whose spectra consist of three bright lines, one 

 being a Hydrogen line. The third bright line in these spectra is ascribed to the 

 protyle with five electrons, called Protofluorine. Perhaps further evidence 

 would need an interchange of these names. It is possible to build up all the 

 atomic weights by simple groupings of three of these primary elements, these 

 atomic weights being always within the limit of error of the experimental deter- 

 minations by chemical methods. In this process, allowance is made for the fact 

 that although the weight is mainly due to positive electricity, some portion is 

 c-iiised by electrons. It is found that a combination, for example, of one atom 

 of protoliuorine with one of nebulium — a combination which would readily occur 

 and be very permanent — would have a molecular weight of 3988, which is in 

 close accord with 3'99, the atomic weight of helium. It is easy to see why this 

 should be an inert gas. Moreover, its appearance immediately after the three 

 bright lines in the slightly more developed nebulae is a striking confirmation of 

 the theory. 



The author then proceeded with a detailed discussion of the inert gases and 

 emanations, and showed that a very similar constitution, in terms of certain con- 

 stantly-recurring groups of protyles with definite valencies, could be assigned 

 all the inert gases, known and unknown. This theory leads to an atomic weight 

 of 2268 for radium, indicating that its ultimate product is lead, and also to the 

 conclusion that the thorium emanation is that of radium with the groupings of 

 protyles arranged differently. 



From Russ's experiments it becomes possible to find the molecular weight of 

 actinium emanation. It was shown that this emanation fits exactly into one of 

 the vacant spaces in the Neon group of gases, and the corresponding atomic 

 weight of actinium is 165-6. Actinium, therefore, falls between terbium and 

 erbium, and is a member of the same group of elements as radium. 



The oroupings of protyles in the inert gases are only a part of a systematic 

 set for all the elements. If the protyles are denoted by Cn, H, Nu, Pf, and 

 unknown gases by X r , we have the following table :— 



