rendered particularly interesting by the fact that it is headed by
nitrogen, which--like the air, of which it forms so large a part--pervades
so many of the bodies we are studying. What is there in nitrogen which
renders it so inert as to conveniently dilute the fiery oxygen and make it
breathable, while it is so extraordinarily active in some of its compounds
that it enters into the most powerful explosives? Some chemist of the
future, perhaps, will find the secret in the arrangement of its constituent
parts, which we are able only to describe.

[Illustration: PLATE XII.]

NITROGEN (Plate XII, 1) does not assume the cubical form of its relatives,
but is in shape like an egg. Referring again to our 1895 investigations, I
quote from them. The balloon-shaped body (see 4 _a_) floats in the middle
of the egg, containing six small spheres in two horizontal rows, and a long
ovoid in the midst; this balloon-shaped body is positive, and is drawn down
towards the negative body _b_ (see 4 _b_) with its seven contained spheres,
each of which has nine atoms within it--three triads. Four spheres are
seen, in addition to the two larger bodies; two of these (see 4 _d_), each
containing five smaller globes, are positive, and two (see 4 _c_)
containing four smaller globes, are negative.

NITROGEN: Balloon 110
Oval 63
2 bodies of 20 atoms 40
2 " " 24 " 48
----
Total 261
----
Atomic weight 14.01