indirectly: doubtful [from comparison of specific heats of some compounds with those of other alkali metals] indirectly doubtful [comparison of specific heats of compounds of Sr, Ca, and Ba] Isomorphism: compounds compared [See note 4, p. 84.] Salts of HCrO, with those of H.MnO, and H2TeO1, Cr2O3 with Al2O3, Mn,O, and Fe MnO3 with Al,O,, Cr2O, and FeO3, RaMnO, with RCro and R2TeO., RMnO, with KCIO FeO3 and derivatives with Al2O, CrŎ3. MnO, and derivatives, some Fe salts with those of Ni, Co, and Cu Ni with Co compounds, some Ni compounds with those of Fe (ferrous salts) Co with Ni compounds, some Co compounds with those of Fe (ferrous salts) most Cu compounds with those of Ni and Co, some with Fe (ferrous) compounds, Cu with Ag compounds of type R2O Zn compounds with those of Mg and Mn Ga alum with other alums As compounds with those of Sb and Bi, organic compounds of As with those of N, P, and Sb, arsenates with phosphates and vanadates Se with S compounds Bromides with analogous compounds of Cl and I Rb compounds with those of other alkali metals Sr compounds with those of Ca and Ea, and with some Pb salts sp. heats of a few compounds de- Yt compounds with those of other termined directly [? too low] NbCls, NbOCI, directly [? too high] earth metals ZrO, with TiO, ThO,, SnO, and SiO2 Nb with Ta compounds, Nb fluorides and oxyfluorides with Mo do. do. Mo with W compounds, some salts of H,MoO, with those of HCrO, Mo with Nb fluorides and oxyfluorides VIII Remarks [See note C, p. 84.] Rb. From analogies between Rb (and its salts) and the metals of the alkalis, the formulæ RbCl, Rb2O, &c. are most probably correct: if so, the atomic weight of Rb is to be taken as equal to its combining weight. Sr. The atomic weight of strontium must be taken as 43'65 X 2 = 87'3 if the formulæ of its salts are to become analogous to those of the Ba and Ca salts. Yt. Atomic weight probably = 29'87 X3896 because of analogy of Yt salts with those of earth metals. 6 YTTERBIUM none TANTALUM TaCls TUNGSTEN WOCI, WC, WCle [See note A, p. 84.] most Rh compounds with those of Ru, Pd, Ir, Pt and Os most Ru compounds with those of Rh, Pd, Ir, Pt and Os most Pd compounds with those of Ru, Rh, Ir, Pt and Os some Ag compounds with those of Na and other alkali metals, Ag with Cu compounds of type RO, a few Ag and Au compounds some Cd compounds with those of Be and Zn some In compounds with those of Cd and Be SnO2 with TiO2, ZrO2 and ThO, Sb compounds with those of As and Bi Iodides with analogous compounds of Cl and Br most Te compounds with those of S and Se Cs compounds with those of other metals of alkalis Ba compounds with those of Ca and Sr most La compounds with those of Ce, Di, Er and Yt, some compounds of these metals with Ca compounds sp. heats of a few compounds [? a few Yb compounds with those determined of other earth metals] Ta with Nb compounds W with Mo compounds, some salts of HWO, with those of HCrO, and H2TeO directly Os, Ir and Pt compounds with those of Ru, Rh and Pd A. As the method based on isomorphism of compounds is chiefly used as a means of verifying values assigned to atomic weights by other methods, no numbers are given in column IV., but merely an indication of the various compounds which have been compared crystallographically, and on which, arguments for or against a given value for the atomic weights in column v. have been, or may be, based. B. This column (VI.) is not to be regarded as containing anything like a complete summary of the processes employed for determining the combining numbers of the elements; only the more important processes are indicated;references are given to the original papers. A complete account of all researches on this subject will be found in A Recalculation of the Atomic Weights, by F. W. Clarke [Part v. of the Constants of Nature published by the Smithsonian Institution], and also in Die Atomgewichte der Elemente, by L. Meyer and K. Seubert [Leipzig, 1883]. C. When the atomic weight given in column v. section (2) is a multiple of the combining number in column VII., no number being given in section (1) of column v., it is to be inferred that, besides the argument drawn from the value of the specific heat of the element in question, there are other chemical reasons for adopting the special multiple which appears in V. (2): these reasons may be broadly described as based on analogies between salts of the given element and salts of other elements, the atomic weights of which have been established by the two leading physical methods. |