XXIV, No. 33, and issued on January 25, 1908, the weight of
hydrogen is now taken at 1.008 instead of at 1. This would slightly raise
all the orthodox weights; thus aluminium rises from 26.91 to 27.1, antimony
from 119.34 to 120.2, and so on.
* * * * *
XI.
RADIUM.
[Illustration: PLATE XXII.]
Radium has the form of a tetrahedron, and it is in the tetrahedral groups
(see article IV) that we shall find its nearest congeners; calcium,
strontium, chromium, molybdenum resemble it most closely in general
internal arrangements, with additions from zinc and cadmium. Radium has a
complex central sphere (Plate XXII), extraordinarily vivid and living; the
whirling motion is so rapid that continued accurate observation is very
difficult; the sphere is more closely compacted than the centre-piece in
other elements, and is much larger in proportion to the funnels and spikes
than is the case with the elements above named; reference to Plate VIII
will show that in these the funnels are much larger than the centres,
whereas in radium the diameter of the sphere and the length of the funnel
or spike are about equal.
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