64 PRESIDENT’S ADDRESS—SECTION B. 
atomic weight is practically constant, but which differ in weight 
among themselves to a small but finite extent. This, in his view, 
would be the natural consequence of the generation of the elements 
from a primordial matter, and if I understand him aright, he 
believes that in such groups as that of the cerium metals, and 
others of which the members closely resemble one another, we 
have traces remaining of an imperfect differentiation into the 
distinct substances we have been accustomed to call elements. 
In his Faraday lecture, delivered last year before tae Chemical 
Society of London, Mendeléeff criticises somewhat severely these 
views as to the character and origin of the elements. He objects 
to the representation of the periodic law in the form of curves as 
used by Reynolds, Crookes and Haughton, on the ground that a 
curve as ordinarily used indicates a continuous and unbroken 
series of points, and that, therefore, at any and every point of such 
a curve, there should be a corresponding element—in other words, 
this method of representation implies an infinite number of 
elements—so at least I understand his objection. It would 
appear, however, that this criticism is based upon a misconcep- 
tion of the real object of these so-called curves, which, I take it, 
are not intended to be understood in a purely mathematical sense, 
but simply as graphic representations of the periodic law, which 
enable us to see more clearly its prominent features. He points 
out further that the analogy between the series of elements and 
hydrocarbon radicles, worked out by Carnelley (though previously 
indicated by Pelopidas) is weak in this respect, that whereas the 
series of natural elements involves an increase of mass as we pass 
from one member to another the series of hydrocarbon radicles 
involves a decrease, and that therefore there is no true identity 
of periodicity in the two cases. This statement, is of course, 
involved in Carnelley’s assumption of a negative atomic weight. 
As regards the existence of felium, an element supposed by 
Lockyer to exist in the sun, he points out that no attention 
is paid to the fact that the helium line is seen only in the 
spectrum of the solar protuberances, nor to the fact that the same 
line is wanting among the Fraunhofer lines of the solar spectrum, 
and therefore does not answer to the fundamental conception of 
spectrum analysis, and he further criticises other statements 
regarding the alleged spectroscopic indications of the decompo- 
sition of the elements. He does not, however, attempt to 
controvert Crookes’ results, but says :—‘ From the foregoing 
as well as from the failures of so many attempts at finding 
in experiment and speculation a proof of the compound character 
of the elements and of the existence of primordial matter, it is 
evident, in my opinion, that this theory must be classed among 
mere utopias.” 
The supposition of Carnelley that the ether may be one of the 
forms of the primordial matter has been already alluded. to. 
