Atomic weight 69.50
Number weight 1260/18 70.00
INDIUM (Plate XIII, 3) repeats the segments of gallium exactly, save in the
substitution of a sixteen-atomed body for the seven-atomed cone of the
left-hand segment, and a fourteen-atomed body for the five-atomed
corresponding one in gallium. But each funnel now has three segments
instead of two; three funnels out of the six contain two segments of type A
and one of type B; the remaining three contain two of type B, and one of
type A.

INDIUM: Segment A 121 atoms
Segment B 107 "
3 funnels of 2 A and 1 B ([242 + 107] 3) 1047
3 " " 2 B and 1 A ([214 + 121] 3) 1005
----
Total 2052
----
Atomic weight 114.05
Number weight 2052/18 114.00
The corresponding negative group, phosphorus, arsenic, and antimony, run on
very similar lines to those we have just examined.

[Illustration: PLATE XIV.]

PHOSPHORUS (Plate XIV, 1) offers us a very curious arrangement of atoms,
which will give some new forms in breaking up. Two segments are in each
funnel, in fact the only two of group III _a_ which do not show this
arrangement, or a modification thereof, are aluminium and arsenic.

PHOSPHORUS: Left segment 50 atoms
Right segment 43 "
--
93
6 funnels of 93 atoms 558
Atomic weight 30.77
Number weight 558/18 31.00
ARSENIC (Plate XIV, 2) resembles aluminium in having eight internal
sub-divisions in a funnel, and the ovoids which form the top ring are
identical, save for a minute difference that in aluminium the ovoids stand
the reverse way from those in arsenic. It will be noted that in the former
the top and bottom triangles of atoms have the apices upwards, and the
middle one has its apex downwards. In arsenic, the top and bottom ones
point downwards, and the middle one upwards. Arsenic inserts sixteen
spheres between the ovoids and globe shown in aluminium, and thus adds no
less than one hundred and forty-four atoms to each funnel.

ARSENIC: 6 funnels of 225 atoms 1350
Atomic weight 74.45
Number weight 1350/18 75.00
ANTIMONY (Plate XIV, 3) is