566 The Evolution of Matter 
seemed quite unalterable, and the atoms, of which each element in 
modern view is composed, bore to Clerk Maxwell, writing about 
1870, “the stamp of manufactured articles” exactly similar in kind, 
unchanging, eternal. 
Nevertheless throughout these years, on the whole so unfavourable 
to its existence, there persisted the idea of a common origin of the 
distinct kinds of matter known to chemists. Indeed, this idea of unity 
in substance in nature seems to accord with some innate desire or 
intimate structure of the human mind. As Mr Arthur Balfour well 
puts it, “There is no @ priori reason that I know of for expecting 
that the material world should be a modification of a single medium, 
rather than a composite structure built out of sixty or seventy 
elementary substances, eternal and eternally different. Why then 
should we feel content with the first hypothesis and not with the 
second? Yet so it is. Men of science have always been restive under 
the multiplication of entities. They have eagerly watched for any sign 
that the different chemical elements own a common origin, and are all 
compounded out of some primordial substance. Nor, for my part, do I 
think that such instincts should be ignored...that they exist is certain ; 
that they modify the indifferent impartiality of pure empiricism can 
hardly be denied*.” 
When Dalton’s atomic theory had been in existence some half 
century, it was noted that certain numerical relations held good 
between the atomic weights of elements chemically similar to one 
another. Thus the weight (88) of an atom of strontium compared 
with that of hydrogen as unity, is about the mean of those of 
calcium (40) and barium (137). Such relations, in this and other 
chemical groups, were illustrated by Beguyer de Chancourtois in 
1862 by the construction of a spiral diagram in which the atomic 
weights are placed in order round a cylinder and elements chemically 
similar are found to fall on vertical lines. 
Newlands seems to have been the first to see the significance of 
such a diagram. In his “law of octaves,” formulated in 1864, he 
advanced the hypothesis that, if arranged in order of rising atomic 
weight, the elements fell into groups, so that each eighth element was 
chemically similar. Stated thus, the law was too definite; no room 
was left for newly-discovered elements, and some dissimilar elements 
were perforce grouped together. 
But in 1869 Mendeléeff developed Newland’s hypothesis in a form 
that attracted at once general attention. Placing the elements in 
} Report of the 74th Meeting of the British Association (Presidential Address, Cambridge 
1904), p. 9, London, 1905. 
