*Project Gutenberg*. Public domain.

META-NEON: Six arms of 47 atoms 282

Central
tetrahedra 120

——

Total 402

——

Atomic weight ——

Number weight 402/18 22.33

ARGON (Plate XX, 4, 6 and 7) shows within its arms
the *b* 63 which we met

in nitrogen, yttrium, vanadium and niobium, but not
the “balloon,” which we

shall find with it in krypton and its congeners.

ARGON: Six arms of 99 atoms 594

Central
tetrahedra 120

——

Total
714

——

Atomic weight
39.60

Number weight
714/18 39.66

METARGON (Plate XX, 5, 6 and 7) again shows only an
additional seven atoms

in each arm.

METARGON: Six arms of 106 atoms 636

Central
tetrahedra 120

——

Total
756

——

Atomic weight ——

Number weight 756/18 42

[Illustration: PLATE XXI.]

KRYPTON (Plate XXI, 1 and 4, and Plate XX, 6 and 7)
contains the nitrogen “balloon,” elongated
by its juxtaposition to *b* 63. The central
tetrahedra appear as usual.

KRYPTON: Six arms of 224 atoms 1344

Central
tetrahedra 120

-----

Total
1464

-----

Atomic
weight 81.20

Number
weight 1464/18 81.33

META-KRYPTON differs only from krypton by the substitution
of *z* for *y*

in each arm of the star.

META-KRYPTON: Six arms of 231 atoms 1386

Central
tetrahedra 120

-----

Total
1506

-----

Atomic
weight -----

Number
weight 1506/18 83.66

XENON (Plate XXI, 2 and 4, and Plate XX, 6 and 7)
has a peculiarity shared

only by kalon, that *x* and *y* are asymmetrical,
the centre of one having

three atoms and the centre of the other two.
Is this done in order to

preserve the difference of seven from its comrade?

XENON: Six arms of 363 atoms 2178

Central
tetrahedra 120

-----

Total
2298

-----

Atomic
weight 127.10

Number
weight 2298/18 127.66

META-XENON differs from xenon only by the substitution
of two *z*’s for *x*

and *y*.