[285] Reference may be made here to the term "stability limit," introduced by Knorr (_Annalen_, 1896, 293. 88) to indicate that temperature above which liquefaction and isomeric change takes place. As employed by Knorr and others, the term does not appear to have a very precise meaning, since it is used to denote, not the temperature at which these changes can occur, but the temperature at which the change is rapid (vide _Annalen_, 1896, 293. 91; 1899, 306. 334); and the introduction of an indefinite velocity of change renders the temperature of the stability limit also somewhat indefinite. The definiteness of the term is also not a little diminished by the fact that the "limit" can be altered by means of catalytic agents. Since, as we have seen, the stable modification can always undergo isomeric change and liquefy at temperatures above the natural freezing point, but not below that point; and, further, the less stable modification can undergo isomeric transformation and liquefy at temperatures above the eutectic point, but will not liquefy at temperatures below that; it seems to the author that it would be more precise to identify these two points--the natural freezing point and the eutectic point--which are not altered by catalytic agents, with the "stability limits" of the stable and unstable modification respectively. A perfectly definite meaning would thereby be given to the term. In the case of those substances which do not undergo appreciable isomeric change at the temperature of the melting point, the stability limits would be the points G and H, Fig. 60. [286] Cameron, _Journ. Physical Chem._, 1898, 2. 409. [287] Carveth, _Journ. Phys. Chem._, 1898, 2. 159. See also Dutoit and Fath, _Journ. chim. phys_., 1903, 1. 358; Findlay, _Trans. Chem. Soc._, 1904, 85. 403. [288] Hollmann, _Zeitschr. physikal. Chem._, 1903, 43. 129. [289] For other examples of the application of the Phase Rule to isomeric substances, see _Journ. Physical Chem._, vols. 2. _et seq._; Findlay, _Trans. Chem. Soc._, 1904, 85. 403. [290] See Roozeboom, _Zeitschr. physikal. Chem._, 1899, 30. 410. [291] See also Saposchnikoff, _Zeitschr. physikal. Chem._, 49. 688; Kremann, _Monatshefte_, 1904, 25. 1215, 1271, 1311. [292] J. C. Philip, _Journ. Chem. Soc._, 1903, 83. 821. [293] _Cf._ also Paterno and Ampolla, _Gazzetta chim. ital._, 1897, 27. 481. [294] Philip, _loc. cit._, p. 826. [295] Philip, _loc. cit._, p. 829. Compare curves for iodine monochloride, Fig. 42, p. 162. [296] Kuriloff, _Zeitschr. physikal. Chem._, 1897, 23. 676. [297] Ladenburg, _Ber._, 1895, 28. 163; 1991. [298] Roozeboom, _Zeitschr. physikal. Chem._, 1899, 28. 494; Adriani, _ibid._, 1900, 33. 453. [299] Adriani, _Zeitschr. physikal. Chem._, 1900, 33. 453. [300] A. Findlay and Miss E. Hickmans. [301] Kipping and Pope, _Journ. Chem. Soc._, 1897, 71. 993. [302] See Roozeboom, _Zeitschr. physikal. Chem._, 1899, 28. 512; Adriani, _ibid._, 1900, 33. 473; 1901, 36. 168.