SODIUM: Upper part { 12 funnels of 16 each 192 { Central globe 10 Lower part same 202 Connecting rod 14 ---- Total 418 ---- Atomic weight 23.88 Number weight 418/19 23.22 COPPER (Plate VI, 3) introduces an addition in the funnel, that we shall find elsewhere, _e.g._, in silver, gold, iron, platinum, zinc, tin, the triangular arrangement near the mouth of the funnel and adds to the ten atoms in this nineteen more in three additional enclosed bodies, thus raising the number of atoms in a funnel from the sixteen of sodium to forty-five. The number in the central globe is doubled, and we meet for the first time the peculiar cigar or prism-shaped six-atomed arrangement, that is one of the most common of atomic groups. It ought to imply some definite quality, with its continual recurrence. The central column is the three, four, five, four, three, arrangement already noted. COPPER: Upper part {12 funnels of 45 atoms 540 {Central globe 20 Lower part same 560 Connecting rod 19 ---- Total 1139 ---- Atomic weight 63.12 Number weight 1139/18 63.277 SILVER (Plate VI, 4) follows copper in the constitution of five of the bodies enclosed in the funnels. But the triangular group contains twenty-one atoms as against ten, and three ovoids, each containing three bodies with eleven atoms, raise the number of atoms in a funnel to seventy-nine. The central globe is decreased by five, and the prisms have disappeared. The connecting rod is unaltered. SILVER: Upper part {12 funnels of 79 atoms 948 {Central globe 15 Lower part same 963 Connecting rod 19 ---- Total 1945 ---- Atomic weight 107.93 Number weight 1945/18 108.055 (This atomic weight is given by Stas, in _Nature_, August 29, 1907, but it has been argued later that the weight should not be above 107.883.) [Illustration: PLATE VII.]