14 bars of 72 atoms 1008
Atomic weight 55.47
Number weight 1008/18 56.00
IRON (Plate IV, 1, and XVII, 3):

14 bars of 74 atoms 1036
Atomic weight 57.70
Number weight 1036/18 57.55
COBALT (Plate XVII, 4):

14 bars of 76 atoms 1064
Atomic weight 58.30
Number weight 1064/18 59.11
NICKEL (Plate XVII, 4):

(The weight of cobalt, as given in Erdmann's _Lehrbuch_, is 58.55, but
Messrs. Parker and Sexton, in _Nature_, August 1, 1907, give the weight, as
the result of their experiments, as 57.7.)

[Illustration: PLATE XVIII.]

The next sub-group, ruthenium, rhodium, and palladium, has nothing to
detain us. It will be observed that each bar contains eight segments,
instead of the six of cobalt and nickel; that ruthenium and palladium have
the same number of atoms in their upper ovoids, although in ruthenium a
triplet and quartet represent the septet of palladium; and that in
ruthenium and rhodium the lower ovoids are identical, though one has the
order: sixteen, fourteen, sixteen, fourteen; and the other: fourteen,
sixteen, fourteen, sixteen. One constantly asks oneself: What is the