8 REPOBT — 1887. 



ships. For the first time we thus obtained a glance into the mode in 

 which the elements are connected together, but, like so many new dis- 

 coveries, this did not meet with the recognition which we now see it de- 

 serves. But whilst England thus had the honour of first opening up this 

 new path, it is to Germany and to Russia that we must look for the con- 

 summation of the idea. Germany, in the person of Lothar Meyer, keeps, 

 as it is wont to do, strictly within the limits of known facts. Russia, in 

 the person of MendelejeflP, being of a somewhat mere imaginative nature, 

 not only seizes the facts which are proved, but ventures upon prophecy. 

 These chemists, amongst whom Carnelley must be named, agree in placing 

 all the elementary bodies in a certain regular sequence, thus bringing 

 to light a periodic recurrence of analogous chemical and physical pro- 

 perties, on account of which the arrangement is termed the periodic 

 system of the elements. 



In order to endeavour to render this somewhat complicated matter 

 clear to you, I may perhaps be allowed to employ a simile. Let us, if you 

 please, imagine a series of human families, a French one, represented by 

 Dumas, an English one, by name Newlands, a German one, the family of 

 Lothar Meyer, and lastly a Russian one, that of MendelejeflP. Let us next 

 imagine the names of these chemists placed in a horizontal line in the order 

 I have mentioned. Then let us write under each the name of his father, 

 and again, in the next lower line, that of his grandfather, followed by that 

 of his great-grandfather, and so on. Let us next write against each of 

 these names the number of years which has elapsed since the birth of the 

 individual. We shall then find that these numbers regularly increase by 

 a definite amount, i.e., by the average age of a generation, which will be 

 approximately the same in all the four families. Comparing the ages of 

 the chemists themselves we shall observe certain diflPerences, but these are 

 small in comparison with the period which has elapsed since the birth of 

 any of their ancestors. Now each individual in this series of family trees 

 represents a chemical element ; and just as each family is distinguished 

 by certain idiosyncrasies, so each group of the elementary bodies thus 

 arranged shows distinct signs of consanguinity. 



But more than this, it not unfrequently happens that the history and 

 peculiarities of some member of a family may have been lost, even if the 

 memory of a more remote and more famous ancestor may be preserved, 

 although it is clear that such an individual must have had an existence. 

 In such a case Francis Galton would not hesitate from the characteristics 

 of the other members to reproduce the physical and even the mental 

 peculiarities of the missing member; and should genealogical research 

 bring to light the true personal appearance and mental qualities of the 

 man, these would be found to coincide with Galton 's estimate. 



Such predictions and such verifica,tions have been made in the case 

 of no less than three of our chemical elements. Thus, MendelejeflP pointed 

 out that if, in the future, certain lacunae in his table were to be filled, 

 they must be filled by elements possessing chemical and physical pro- 



