82 Mr. Henry Wilde on the 



From the numerous discrepancies and contradictions 

 which present themselves in the classification of the elements 

 when arranged in the regular order of their atomic weights, 

 we have abundant reason to conclude that the notion of a 

 periodic function, in terms of the horizontal series of 

 Mendeleeff, has no more claim for acceptance than the 

 octaves of recurring properties propounded by Newlands. 



I will now point out in what the real value of the classi- 

 fications of Newlands and Mendeleeff consists, and have to 

 express my surprise that no chemist has, up to the present 

 time, come forward to anticipate me in this analysis. 



Long before the classifications of these chemists, the 

 properties of the elements were compared with their 

 atomic weights, and put together in groups. Cooke, Glad- 

 stone, Pettenkofer, Dumas, Odling, and others, subsequently 

 compared the atomic weights of some of these groups, and 

 found many interesting numerical relations subsisting 

 among them. In the tables of Newlands and Mendeleeff 

 it will be seen that there is an approximate arrangement of 

 the elements in natural groups, and in somewhat crude 

 order of their quantivalence. So far as I know, no attempt 

 had previously been made to arrange all the elements in 

 such an order that the relations of the several families could 

 be seen at once. By comparing the members of one group 

 with the homologous ones of the others Mendeleeff per- 

 ceived, from thelarge differencesamong the atomic weights of 

 some of the well-known families of elements, that certain 

 members were missing, the existence and properties of 

 which he was enabled to predict. Gallium, scandium, and 

 germanium have since been discovered, and find their 

 places approximately in the table of Mendeleeff. 



The verification of this prediction has, however, no 

 necessary connexion with the so-called periodic law, as the 

 newly-discovered elements also find their places in my table, 

 which makes no pretence to being a periodic arrangement. 



