somewhat complicated structure, of the same type as that in sodium (Plate
VI, 2), the difference consisting in the addition of one more globe,
containing nine additional atoms. The central globe is the same as in
sodium, but the connecting rod differs. We have here a regular arrangement
of five globes, containing three, four, five, four, three atoms
respectively, whereas sodium has only three bodies, containing four, six,
four. But copper and silver, its congeners, have their connecting rods of
exactly the same pattern as the chlorine rod, and the chlorine rod
reappears in both bromine and iodine. These close similarities point to
some real relation between these groups of elements, which are placed, in
the lemniscates, equi-distant from the central line, though one is on the
swing which is going towards that line and the other is on the swing away
from it.

CHLORINE: Upper part {12 funnels of 25 atoms 300
{Central globe 10
Lower part same 310
Connecting rod 19
----
Total 639
----
Atomic weight 35.473
Number weight 639/18 35.50
(The Atomic Weights are mostly from Erdmann, and the Number Weights are
those ascertained by us by counting the atoms as described on p. 349,
January, and dividing by 18. Prof. T.W. Richards, in _Nature_, July 18,
1907, gives 35.473.)

BROMINE (Plate V, 3).--In bromine, each funnel has three additional bodies,
ovoid in shape, an addition of 33 atoms being thus made without any