Electropositive Elements, above plane of paper, black letters on white ground. Electronegative Elements, below plane of paper, white letters on black ground. Intermediate Elements, in plane of paper, black letters on sectioned ground.] [Illustration: +---------+--------+--------+--------+--------+--------+--------+ | Group | III. | IV. | V. | VI. | VII. | VIII. | | |A B|A B|A B|A B|A B| | +---------+--------+--------+--------+--------+--------+--------+ |Series 6|~Yt~ |~Zr~ |Cb |Mo | |Ru Rh Pd| | | | | | | | | | „ 7| In| Sn| Sb| Te| I| | +---------+--------+--------+--------+--------+--------+--------+ | „ 8|~La~ |~Ce~ |~Pr~ |~Nd~ |~Sa~ |~Eu~ | | | | | | | | | | „ 9| ~Gd~| ~Tb~| ~Dy~| ~Ho~| ~Er~|~Tm~~Yb~| +---------+--------+--------+--------+--------+--------+--------+ | „ 10|~Lu~ | |Ta |W | |Os Ir Pt| | | | | | | | | | „ 11| | | | | | | +---------+--------+--------+--------+--------+--------+--------+ FIG. 6.--PART OF THE PERIODIC TABLE, SHOWING THE POSITIONS ASSIGNED TO THE RARE EARTH ELEMENTS BY BRAUNER IN 1908] Brauner’s conception is also in accord with the physical properties of the elements and their compounds. These vary continuously throughout the group, and show nowhere the sudden transitions which are characteristic of other series in the table. Benedicts[177] has collected all the data bearing on the atomic volumes, and finds that those also vary continuously, with rise in the atomic weights, within quite small limits, all lying between the values for barium and tantalum. In face of all the evidence furnished by physical and chemical properties, however, Brauner[178] has recently reverted to an idea which he put forward in 1881, according to which lanthanum and cerium are placed as usual in Groups III and IV, series 8, whilst the other elements are distributed in order throughout the remaining groups, as shown in Fig. 6. [177] _Zeitsch. anorg. Chem._ 1904, ~39~, 41. [178] _Monats._ 1881, ~3~, 1; _Zeitsch. Elektrochem._ 1908, ~14~, 525.