1 877.] 
The Chemistry of the Future. 
303 
Further instances of “ small series,” each consisting of 
seven members, known or unknown, are the following : — 
No. 4 
. K 
Ca — 
Ti 
V 
Cr 
Mn 
No. 5 . 
. Cu 
Zn — 
— 
As 
Se 
Br 
No. 6 . 
. Rb 
Sr — 
Zr 
Nb 
Mo 
— 
Thus M. Mendeleeff considers that all the functions by 
which the dependencies of the properties of the elements 
on the atomic weights are expressed appear as periodic. 
The properties change in accordance with the increasing 
atomic weights, and are then repeated in a new period with 
the same regularity as in the former. If we examine his 
scheme we must admit that it brings admitted relations into 
a very prominent light. Such groups as fluorine, chlorine, 
bromine, and iodine ; as sulphur, selenium, and tellurium ; 
as nitrogen, phosphorus, arsenic, and antimony ; as calcium, 
strontium, and barium ; or as potassium, rubidium, and 
csesium, — though their respective members are placed in 
different series, — fall into positions which well agree with 
their respective analogies. Even the trinity of the commer- 
cial world — gold, silver, and copper — fall in the same hori- 
zontal line across the series ; gold being a representative of 
its companion metals in a higher series. A further study 
of Table II. will bring to light many more curious instances 
of such representation, which we submit lend a powerful 
support to M. Mendeleeff’s arrangement. 
As a matter of course the mere arranging the elements in 
one arithmetical series would thrust these analogies totally 
out of sight. As completely would they be hidden if the 
series were made to consist of any other number of ele- 
ments. M. Mendeleeff’s classification is shown in two 
tables taken from the translation of his memoir in Liebig’s 
“ Annalen.” He admits that not all the known elements 
can be introduced into the small series. Thus in Table I. 
we see iron, cobalt, nickel, ruthenium, rhodium, palladium, 
osmium, iridium, and platinum forming an appended eighth 
group, concerning which the author remarks that they are 
all grey, all very sparingly fusible, their fusibility increasing 
in each line from iron to nickel, from ruthenium to palla- 
dium, and again from osmium to palladium. Between the 
corresponding members of the even and the odd small series 
(except the two first) there is a distinct difference, whilst the 
corresponding members of the even and again of the odd, 
series show a close analogy. 
