296 The Chemistry of the Future. [July, 
finding ourselves on the road towards a decrease in the 
number of our elements, we shall have another, or perhaps 
two more, to account for and to harmonise. 
We now pass to the consideration of researches having 
no direct: connection with the question we have just been 
handling, but which still indirectly testify in favour of the 
compound nature of our so-called elements. A law has 
been proposed which exhibits these “ elements” not as a hap- 
hazard assemblage of independent bodies, whose number, 
properties, and atomic weights might have been other than 
we find them, but as a definite series, or rather group of 
series, whose members bear to each other relations somewhat 
similar to the successive grades — e.g., of oxidation — of some 
one supposed element. The law in question, though it does 
not remove the teleological difficulties inherent in the 
respective quantities and the distribution of the simple 
bodies, solves, at any rate, some of the hitherto unanswered 
questions which they have put before us. It does more ; it 
enables us to declare not merely that a link is wanting in 
the series, but to foretell with tolerable accuracy not alone 
its atomic weight and its specific gravity, but even certain 
of its reactions. The prevision of phenomena not yet ob- 
served has been rightly declared by methodologists to be one 
of the principal distinctions between a science, in the strict 
sense of the term, and a mere accumulation of unorganised 
knowledge. We still hear mention, from time to time, of 
the splendid triumph achieved by Astronomy, when Leverrier 
—having from certain observed faCts deduced the existence 
of a planet as yet unknown — was able to calculate its dis- 
tance, its mass, its orbit and probable position, and when 
his announcements were found verified on the telescopic 
examination of the part of the heavens indicated. Such a 
fulfilment of his forecasts was a verification of astronomical 
science perfectly intelligible to the outside public. Prof. 
Mendeleeff, by the application of his “ periodic law,” was 
able to foretell distinctly, in 1869, the properties of a metal 
then unknown, to which he gave the name of “eka alumi- 
nium.” On the evening of August 27th, 1875, M. Lecoq de 
Boisbaudran, being engaged with the examination — chemical 
and speCtroscopic — of a blende from the mine of Pierrefitte, 
discovered a new metal, to which he has given the 
name of “ gallium,” in honour of his country. He does 
not appear to have been acquainted with the predictions 
of M. Mendeleeff, which, till their startling verification, had 
not by any means attracted the attention which they un- 
doubtedly merit. The more thoroughly, however, M. Lecoq 
