significance of these minute changes? Further investigators will probably
discover the answer.

14 bars of 132 atoms 1848
Atomic weight 100.91
Number weight 1848/18 102.66
RUTHENIUM (Plate XVIII, 1):

14 bars of 134 atoms 1876
Atomic weight 102.23
Number weight 1876/18 104.22
RHODIUM (Plate XVII, 2):

14 bars of 136 atoms 1904
Atomic weight 105.74
Number weight 1904/18 105.77
PALLADIUM (XVIII, 3):

The third sub-group, osmium, iridium and platinum, is, of course, more
complicated in its composition, but its builders succeed in preserving the
bar form, gaining the necessary increase by a multiplication of contained
spheres within the ovoids. Osmium has one peculiarity: the ovoid marked _a_
(XVIII, 4) takes the place of axis in the upper half of the bar, and the
three ovoids, marked _b_, revolve round it. In the lower half, the four
ovoids, _c_, revolve round the central axis. In platinum, we have marked
two forms as platinum A and platinum B, the latter having two four-atomed
spheres (XVIII, 6 _b_) in the place of the two triplets marked a. It may
well be that what we have called platinum B is not a variety of platinum,
but a new element, the addition of two atoms in a bar being exactly that
which separates the other elements within each of the sub-groups. It will