144 



SIB, WILLIAM EAMSAY 



liquid. This leads to the supposition that its structure must be 

 simpler than that of hydrogen. We are accustomed to believe 

 that the polymerisation of a substance raises its boiling point, 

 and accordingly since hydrogen gas is the polymer of the unknown 

 atomic hydrogen, its liquefaction is possible. 



In support of the hypothesis of the mono-atomicity of helium 

 may also be cited its extraordinary conductivity for electricity, its 

 feeble refractivity for light and its unexpected rapidity of diffusion. 

 As it possesses exceptional properties, we are led to conclude that 

 its molecular constitution is different from that of other gases. 



With regard to the position of argon in the periodic scheme 

 it is sufficient to indicate that if it possesses an atomic weight 

 higher than that of the element which succeeds it in the table, 

 namely potassium, it is not alone in this peculiarity, for the atomic 

 weight of tellurium is undoubtedly above that of iodine, its suc- 

 cessor in the table. 



Admitting then that the atomic weight of helium is about 4, 

 and that the atomic weight of argon is about 40, the difference 

 between these two figures is 36. Now this is just the difference 

 observable among the members of the following series : 



Fluorine 19 



16*5 



Chlorine 35'5 



19-5 



Manganese 55 



Oxygen 

 Sulphur 

 Chromium 



16 



16 

 32 



20-3 

 52-3 



Carbon 12 Boron 11 



16-3 16 



Silicon 28*3 Aluminium 27 



19'8 17-1 



Titanium 48' 1 Scandium 44' 1 



Lithium 

 Sodium 



16 



23 



16-1 

 Potassium 39*1 



Helium 



Argon 



16 



20 



20 



40 



