158 POPULAR SCIENCE MONTHLY. 



groups." "The difference between the number of the lowest member 

 of a group and that immediately above it is seven; in other words, the 

 eighth element starting from a given one, is a kind of repetition of 

 the first, like the eighth note of an octave in music." While this 

 regularity appeared in the case of the elements of low atomic weight, 

 it failed when applied to many of those elements which have a higher 

 weight, and also in the case of iron, cobalt and nickel. These three 

 metals seem to break in upon the octaves, and must be left out of 

 account before the law of octaves can be used. This irregularity New- 

 lands noticed, enunciating his law in the words: "The numbers of 

 analogous elements, ichen not consecutive, differ by seven, or by some 

 multiple of seven." By 'number' he means merely the number of the 

 element when all are arranged in a series in the order of their atomic 

 weight. There was thus here, as in the work of De Chancourtois, the 

 vision of a certain periodicity in the actual arrangement of the elements, 

 and the recognition of the fact that in some way there is a connection 

 between the properties of an element and its atomic weight. But there 

 seemed to be no suspicion that all the properties of an element are a 

 function, much less that they are a periodic function of its atomic 

 weight. 



It may seem strange ■ to us that the work of these two pioneers 

 should have been received with almost complete indifference by chem- 

 ists. This results in part, at least, as has been pointed out by Men- 

 deleefl', from the too-limited application of Newlands's law. Relations 

 were brought out between little groups of elements, like Dobereiner's 

 triads, but comparisons were not made between dissimilar elements, 

 and even the groups made up by taking the seventh elements often 

 contained those which were far from being similar in their properties. 

 Thus we find the first, and hence analogous, elements of his eight 

 octaves as follows: Hydrogen, fluorin, chlorin, cobalt-nickel, bromin, 

 palladium, tellurium, platinum-iridium. Such a grouping as this could 

 hardly be expected to appeal strongly to chemists, especially as iodin, 

 an element which obviously belongs with fluorin, chlorin and bromin, 

 is relegated to the seventh group of elements. The lack of enthusiasm 

 on the part of chemists at the reception of Newlands's work may be 

 judged from an incident. When his paper was read at the meeting 

 of the Chemical Society, one of the members present asked of Professor 

 Newlands whether he had ever tried arranging the elements according 

 to the order of their initial letters. 



The Periodic Law in its present form was first enunciated by Pro- 

 fessor Dmitri IMendeleeff, in 1869, in a paper read before the Russian 

 Physico-Chemical Society. It is true that five years earlier Lothair 

 Meyer had published in the first edition of his ']\Iodern Theory of 

 Chemistry' a list of tlie elements arranged according to atomic weights. 



