306 
The Chemistry of the Future. 
[July, 
will figure as the representative of indium ; thallium, of 
tin ; lead, of antimony ; and bismuth, of tellurium ; changes 
which will not commend themselves to the approval of 
chemists. Altogether we find that the difference between 
the successive atomic weights, in parts of the series where 
M. Mendeleeff does not suspeCt — or at least does not 
indicate — an absent element, ranges from i to 5. What 
will then become of the interesting harmonies which the 
scheme exhibits if some undiscovered element should crop 
up to fill some of the larger of these intervals ? We cer- 
tainly do not find that the author shows any reason why 
such an event should be improbable. M. Mendeleeff him- 
self declares that the Periodic Law cannot be harmonised 
with the Atomic theory without inverting known faCts. 
It will, we think, be evident to the reader that — splendidly 
as the discovery of gallium has fulfilled the deductions 
drawn from the law under consideration — the subject is 
still in its infancy, and that future research is abundantly 
needed to confirm, to modify, or to extend. We should 
suggest to chemists and physicists a course parallel to what 
we have recommended to biologists in the case of the 
Darwinian hypothesis. We would say — Take up the law 
provisionally, and work with it. One of the most essential 
steps is the search for “ eka-silicium,” conducted, as the 
author proposes, by the spedtroscopic examination of titan- 
iferous minerals and residues. The contents of certain 
sealed papers which M. Lecoq ae Boisbaudran has deposited 
with the Institute, and in which he has explained his special 
ideas on the classification of the elementary bodies, must be 
awaited with interest. Readers who would wish to pursue 
this subjedt further will find detailed information in the 
“Journal de la Soc. Chimique Russe ” (i., p. 60) ; in Liebig’s 
“ Annalen ” (Supplement-Band viii., p. 183, 1871) ; and, if 
they understand the Russian language, in M. Mendeleeff’s 
work, “ Foundations of Chemistry ” (vol. ii.). As far as the 
“ periodic law ” may be considered established, it seems to 
us most decidedly to contradidt the hypothesis of some sixty 
primordially distinct bodies, and to exhibit our present ele- 
ments as produdts of the evolution of something to us yet 
unknown. For that something it must be the task of 
chemists to search. 
