Law of Atomic Weights, 113 



Ramsay, followed by the discovery of four other elementary 

 gases — helium, neon, krypton, and xenon — by Sir William 

 Ramsay. These new elements occupy the five places which 

 had several years earlier been proved to be a necessary part 

 of the Mendeleeff series. Moreover, there can be little doubt 

 that the very unusual chemical behaviour of these new 

 elements, is a consequence of their occupying a position which 

 has sandwiched them between the elements on sesqui-radius 15 

 (fluorine, chlorine, bromine, and iodine) in which the electro- 

 negative condition rises to its highest intensity, and the 

 elements on sesqui-radius 1 (lithium, sodium, potassium, 

 rubidium, and caesium) which are the most electro-positive 

 known. 



The paper above referred to was not printed by the Royal 

 Society ; but while it was sub judice the Bath meeting of the 

 British Association was held, at which, with the permission 

 of the Secretaries of the Royal Society, I gave an account of 

 tbe investigation and exhibited on a large scale two of the 

 diagrams*, one of them that which is here reproduced in 

 PL IV., and the other a diagram illustrating the laws of 

 the deviations. I also distributed either at the meeting or 

 since some hundreds of copies of the diagram which accom- 

 panies this letter, which I had had printed for the purpose, 

 as well as the following " Observations " in explanation of it. 



These have recently been referred to by more than one 

 scientific manj, and it has been suggested to me that they 

 ought to be more satisfactorily published. I therefore ven- 

 ture to request you to admit them into the Philosophical 

 Magazine, so as to ensure their being accessible to everyone 

 interested in the matters discussed in them, as these are likely 

 to attract more attention now than they did fourteen years ago. 

 I am, Gentlemen, 



30 Ledbury Road, W., Faithfully yours, 



August 16, 1902. G Johnstone Stoney. 



The following is a copy of the document which was 

 circulated in 1888, with the diagram reproduced in Plate IV. 



' ; Observations on the accompanying Diagram illustrating 

 the Logarithmic (or the Elliptic) Law of Atomic Weights 

 " 1. The accompanying diagram is sent in advance by the 



* One of these large diagrams I gave to Professor Hartley shortly after 

 the meeting, and I have ascertained that it is still in existence in the 

 collection of chemical diagrams in the Royal College of .Science in Dublin. 



f See Prof. Emerson Reynolds's Presidential Address to the Chemical 

 -Society in last March (Transactions of the Chemical Society 1892, 

 vol. lxxxi. p. 614) ; and Dr. J. H. Vincent's paper in the Phil. Mag. of 

 last J ul v, p. 105. 



