The "nitrogen balloon" occupies the third place in the funnel, now showing its usual shape in combination, while the _b_ globe (see 4 _b_) of scandium takes on a lengthened form below it. The central globe presents us with two tetrahedra, recalling one of the combinations in gold (see Plate VII _d_), and differing from that only by the substitution of two quartets for the two triplets in gold. One funnel of yttrium contains exactly the same number of atoms as is contained in a gaseous atom of nitrogen. Further, _a_, _b_, and _d_ are all nitrogen elements. We put on record these facts, without trying to draw any conclusions from them. Some day, we--or others--may find out their significance, and trace through them obscure relations. YTTRIUM: 6 funnels of 261 atoms 1566 Central globe 40 ---- Total 1606 ---- Atomic weight 88.34 Number weight 1606/18 89.22 The corresponding negative group, of nitrogen, vanadium and niobium, is 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.