THE PLATONIC SOLIDS

Some of our readers may be glad to have a drawing of the Platonic solids, since they play so large a part in the building up of elements. The regular solids are five, and five only; in each:

(1) The lines are equal.
(2) The angles are equal.
(3) The surfaces are equal.

Illustration

It will be seen that the tetrahedron is the fundamental form, the three-sided pyramid on a triangular base, _i.e._, a solid figure formed from four triangles. Two of these generate the cube and the octahedron; five of these generate the dodecahedron and the icosahedron.

The rhombic dodecahedron is not regular, for though the lines and surfaces are equal, the angles are not.

Mr. C. Jinarajadasa[1] writes:

The asterisk put before metargon in the list of elements should be omitted, for metargon had been discovered by Sir William Ramsey and Mr. Travers at the same time as neon (see _Proceedings of the Royal Society_, vol. lxiii, p. 411), and therefore before it was observed clairvoyantly. It is not, however, given in the latest list of elements in the Report of November 13, 1907, of the International Atomic Weights Commission, so it would seem as though it were not yet fully recognised.

Neon was discovered in 1898 by Ramsey and Travers, and the weight given to it was 22. This almost corresponds with our weight for meta-neon, 22.33; the latest weight given to neon is 20, and that corresponds within one-tenth to our weight, 19.9. From this it would seem that neon was examined in the later investigations and meta-neon in the earlier.

He says further on a probable _fourth_ Interperiodic Group:

Thinking over the diagrams, it seemed to me likely that a fourth group exists, coming on the paramagnetic side, directly under iron, cobalt, nickel, just one complete swing of the pendulum after rhodium, ruthenium, palladium. This would make four interperiodic groups, and they would come also _periodically_ in the table too.

I took the diagram for Osmium, and in a bar postulated only three columns for the first element of the new groups, _i.e._, one column less than in Osmium. This would make 183 atoms in a bar; the new group then would follow in a bar, 183, 185, 187. Here I found to my surprise that the third postulated group would have a remarkable relation to Os, Ir, Pt.

Thus Os.--245 (in a bar); less 60 = 185 Ir. 247 less 60 = 187 Pt. 249 less 60 = 189 But strange to say _also_ Ruthenium (bar) 132 less 60--72 Rhodium 134 less 60--74 Palladium 136 less 60--76 But 72, 74, 76, are Iron, Cobalt and Nickel.

So there does probably exist a new group with bars (183), 185, 187, 189, with atomic weights.

X=bar 185; atoms 2590, wt. 143.3 Y= 187, 2618, wt. 145.4 Z= 189, 2646, wt. 147.0. They come probably among the rare earths. Probably also Neodymium and Praseodymium are two of them, for their weights are 143.6, 140.5.

15.11.2007. 17:02

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