----
Atomic weight 6.98
Number weight 127/18 7.05
POTASSIUM (Plate XIX, 2) consists of nine radiating lithium spikes, but has
not petals; its central globe contains one hundred and thirty-four atoms,
consisting of the "nitrogen balloon," encircled by six four-atomed spheres.

POTASSIUM: 9 bars of 63 atoms 567
Central globe 134
----
Total 701
----
Atomic weight 38.94
Number weight 701/18 38.85
(The weight, as determined by Richards [_Nature_, July 18, 1907] is
39.114.)

RUBIDIUM: (Plate XIX, 3) adds an ovoid, containing three spheres--two
triplets and a sextet--to the lithium spike, of which it has sixteen, and
its central globe is composed of three "balloons."

RUBIDIUM: 16 spikes of 75 atoms 1200
Central globe 330
----
Total 1530
----
Atomic weight 84.85
Number weight 1530/18 85.00
The corresponding negative group consists only of fluorine and manganese,
so far as our investigations have gone.