22 , THE NEW KNOWLEDGE. 



You will notice that the mean of the first and third atomic 

 weights is not exactly the atomic weight of the middle one, 

 but the approximation is so close as to excite remark and 

 to inspire the conviction that there is some hidden reason 

 for it. At any rate our suspicion that the atoms are in 

 some way or other related to one another is confirmed, and 

 it will therefore surprise us less to find ourselves confronted 

 by a new discovery in 



THE PERIODIC LAW. 



The Periodic System of the Elements, as we now have 

 it, was discovered independently and almost simultaneously 

 by the Russian, Mendeleeff, and the German, Lothar Meyer; 

 though the germ of the discovery undoubtedly lay in the 

 Octaves of Newlands. 



In 1863 Mr. John Newlands pointed out in a brief letter 

 to the Chemical News that if the elements be arranged in 

 the order of their atomic weights, beginning with hydro- 

 genI, and ending with uranium 240, in a tabular form, 

 they naturally fall into such groups that elements similar 

 to one another in chemical behaviour occur in the same 

 columns; and that, moreover, the number of elements be- 

 tween any one and the next similar one is seven. In other 

 words, members of the same groups stand to one another 

 in the same relation as the extremities of cne or more oc- 

 taves in music ! This leads us. to think that not only may 

 there be a relation between these little fundamentals of the 

 universe but a veritable harmony. 



Briefly and technically, the law states that "the prop- 

 erties of an element are a periodic function of its atomic 

 weight." 



This is a very concise statement indeed of an extraordi- 

 nary fact. The statement means no more nor less than this; 



