six duads and two units as hyper compounds. It will be seen that, complex
as gold is, it is composed of constituents already familiar, and has iodine
and occultum as its nearest allies.

II AND IIa.--THE TETRAHEDRAL GROUPS.

II.--This group consists of beryllium (glucinum), calcium, strontium and
barium, all diatomic, paramagnetic and positive. The corresponding group
consists of oxygen, chromium, molybdenum, wolfram (tungsten) and uranium,
with a blank disk between wolfram and uranium: these are diatomic,
paramagnetic, and negative. We have not examined barium, wolfram, or
uranium.

[Illustration: PLATE VIII.]

BERYLLIUM (Plate III, 2, and Plate VIII, 1). In the tetrahedron four
funnels are found, the mouth of each funnel opening on one of its faces.
The funnels radiate from a central globe, and each funnel contains four
ovoids each with ten atoms within it arranged in three spheres. In the
accompanying diagrams one funnel with its four ovoids is shown and a single
ovoid with its three spheres, containing severally three, four, and three
atoms, is seen at the left-hand corner of the plate (7 _a_). The members of
this group are alike in arrangement, differing only in the increased
complexity of the bodies contained in the funnels. Beryllium, it will be
observed, is very simple, whereas calcium and strontium are complicated.

BERYLLIUM: 4 funnels of 40 atoms 160
Central globe 4
----
Total 164