[88] Monatshefte, 1888, 9. 435.
[89] Gattermann, Ber., 1890, 53. 1738.
[90] Zeitschr. physikal. Chem., 1889, 4. 468; Annalen der Physik, 1900 [4], 2. 649.
[91] Quincke, Annalen der Physik, 1894 [3], 53. 613; Tammann, Annalen der Physik, 1901 [4], 4. 524; 1902, 8. 103; Rotarski, ibid., 4. 528.
[92] Annalen der Physik, 1900 [4], 2. 649.
[93] Annalen der Physik, 1902 [4], 8. 911.
[94] See, more especially, O. Lehmann, Annalen der Physik, 1900 [4], 2. 649; Reinitzer, Sitzungsber. kaiserl. Akad. zu Wien., 1888, 94. (2), 719; 97. (1), 167; Gattermann, loc. cit.; Schenck, Zeitschr. physikal. Chem., 1897, 23. 703; 1898, 25. 337; 27. 170; 1899, 28. 280; Schenck and Schneider, ibid., 1899, 29. 546; Abegg and Seitz, ibid., 1899, 29. 491; Hulett, ibid., 1899, 28. 629; Coehn, Zeitschr. Elektrochem., 1904, 10. 856: Bredig and Schukowsky, ibid., 3419. For a full account of the subject, the reader is referred to the work by Lehmann, Flüssige Kristalle (Engelmann, 1904), or the smaller monograph by Schenck, Kristallinische Flüssigkeiten und flüssige Kristalle (Engelmann, 1905).
[95] A. C. de Kock, Zeitschr. physikal. Chem., 1904, 48. 129.
[96] On account of the fact that all grades of rigidity have been realized between the ordinary solid and the liquid state, in the case both of crystalline and amorphous substances, it has been proposed to abandon the terms "solid" and "liquid," and to class bodies as "crystalline" or "amorphous," the passage from the one condition to the other being discontinuous; crystalline bodies possess a certain regular orientation of their molecules and a directive force, while in amorphous bodies these are wanting (see Lehmann, Annalen der Physik, 1900 [4], 2. 696).
[97] Hulett, loc. cit.