Atomic Theory Wilde. 363 



arithmetical mean of the atomic weights of the second and 

 fourth members.' 



If any man will say that Mr. Wilde compares a law of 

 weight with a law of distance, then we may reply, ' Does 

 the weight not determine the distance ? Is not the atom 

 that which determines the motion of worlds, and the power 

 of suns ? ' 



It may certainly look like presumption in the writer to 

 bring forward any of his own work when leaving out that 

 of his friends ; but these two papers are all that have been 

 published by the Society on the atomic numbers since 

 Dalton and Joule. The author does not pretend to see 

 their bearing, but they have a bearing of a certainty. He 

 sends them to be explained, if he fails to explain them him- 

 self. Only the beginning can be shown, but the results were 

 obtained with care, and seem to indicate a new departure for 

 the atomic theory. The writer had been collecting papers on 

 the subject, a favourite one, when this result was found by him. 

 It led to a new direction of thought, but more practical work 

 has driven him from it for too long a time. It arose from 

 no crotchet, but from a series of most unexpected facts. 

 The first idea was given in 1868 at the Norwich meeting of 

 the British Association, and then published by this Society. 

 Afterwards every experiment was several times repeated 

 with similar results after an interval of ten years, and the 

 following abridgment was published by the Royal Society. 



