Manchester Memoirs, Vol. xlvii. (1903), No.VX. 17 



capable of experimental investigation. Some of the most 

 exact and elaborate determinations of atomic weight have 

 been made with the direct purpose of testing the truth or 

 falsity of Prout's speculation, and science thereby has been 

 notably enriched. The marvellous researches of Stas, for 

 instance, had this specific object in view. The verdict 

 was finally unfavourable to Prout ; at least, the best 

 measurements fail to support his idea ; but it still has 

 advocates who believe that the experimental data are 

 vitiated by unknown errors, and that future investigations 

 will reverse the decision. In science there is no court of 

 last appeal. 



Prout's hypothesis, then, stimulated the determination 

 of atomic weights, and so helped us to a more accurate 

 knowledge of them. It also led to a search for other 

 relations between these constants, and thus paved the way 

 for important discoveries. Dobereiner, Kremers, Dumas, 

 Pettenkofer, Cooke and many other chemists published 

 memoirs upon this theme, but not one of them was general 

 or conclusive.* Groups of elements were compared and 

 relations were brought to light, but an exhaustive study 

 of the question was hardly possible until after Cannizzaro 

 had revised the atomic weights and indicated their proper 

 values. 



In 1865, Newlands presented before the London 

 Chemical Society a communication upon the law of 

 octaves, in which he showed that the elements, when 

 arranged in the order of their atomic weights, exhibited a 

 certain regular recurrence of properties. Unfortunately, 

 his views were not given serious attention, and even met 

 with ridicule, but they contained the germ of a great truth. 



*A very full account of these attempts is given in Venable's book, 

 " The Development of the Periodic Law." Published at Easton, 

 Pennsylvania, in 1896. 



