Tutton, fixed positions of atoms in crystals, 122–124; law of progression of crystal properties in isomorphous series, 121–123, 129; nature of structural units, 134, 135; research on calcium dextro-glycerate, 157, 160; researches on simple and double sulphates and selenates, 121; researches on triphenyl pyrrholones, 105–108 Uniaxial crystals, optic axis of, 165; 60°-prisms of, 164; two refractive indices of, 166, 183 Valentinite, 88 Vanadium family group of elements, 85 Vauquelin, researches on alums, 77 Vicinal faces, 248–254 Vitriols, the, 15, 76, 78 Von Lang, 23, 34 Vorländer, 263; nature of molecules forming liquid crystals, 273 Water, exceptional thermal dilatation of, 47 Water flowers in ice, 47 Water of crystallisation, 76, 78, 79 Wave-length of most luminous part of spectrum, 179 Werner’s fundamental form, 20 Westfeld, 18 Weyberg, 250 White of higher orders, 178 Wollaston’s reflecting goniometer, 63, 81; work on carbonates and sulphates of barium, strontium and lead, 74, 75 Wulff, 250, 252, 253 Zinc sulphate, 76, 78 Zone of crystal faces, 63; circle, 63 PRINTED BY TURNBULL AND SPEARS, EDINBURGH ----- Footnote 1: See page 57 for explanation of indices. Footnote 2: _Proc. Roy. Soc._, 1908, A, 81, 40. Footnote 3: _Comptes Rendus_, 1842, 15, 350, and 1845, 20, 357. Footnote 4: _Comptes Rendus_, 1848, 27, 611, and 1849, 29, 339. Footnote 5: _Jahresbericht_, 1849, 19. Footnote 6: _Comptes Rendus_, 1848, 26, 535. Footnote 7: _Journ. für Prakt. Chemie._, 1865, 94, 286. Footnote 8: _Mem. R. Accad. di Torino_, 2A, 17, 337, and 20, 355. Footnote 9: _Pogg. Ann._, 141, 31. Footnote 10: _Mineralogical Magazine_, 1888, 8, 37. Footnote 11: _Journ. Chem. Soc._, 1896, 69, 507. Footnote 12: _Ann. de Chim. et Phys._, 1848, 24, 28 and 38; also 1850, 28, 56; _Comptes Rendus_, 1848, 26, 535; also 1849, 29, 297; also 1850, 31, 480; also 1853, 37, 162, and 1858, 46, 615. Footnote 13: _Journ. Chem. Soc._, 1891, 315. Footnote 14: _Ibid._, 1897, 989. Footnote 15: _Journ. Chem. Soc._, 1891, 59, 233. Footnote 16: _Ibid._, 1891, 59, 96. Footnote 17: _Phil. Trans. Roy. Soc._, 1895, A, 185, 913. Footnote 18: _Mineralogical Magazine_, 1892, 10, 123. Footnote 19: _Journ. Chem. Soc._, 1906, 89, 413; _Proc. Roy. Soc., A_, 1907, 79, 322. Footnote 20: “Lehrbuch der Allgemeinen Chemice,” vol. 2, part 2, p. 780. Footnote 21: _Phil. Trans._, 1903, A, 202, 459. Footnote 22: _Phil. Trans._, 1903, A, 202, 519. Footnote 23: _Zeitschr. für Kryst._, 1901, 34, 449. Footnote 24: _Loc. cit._, p. 531. Footnote 25: _Sitzungsber. d. Physik. Med. Soc._, Erlangen, 1878, 10, 59. Footnote 26: _Neues Jahrbuch_, 1887, 138. Footnote 27: _Ber. der deutsch. Chem. Ges._, 1907, 40, 1970. Footnote 28: