[272]Adriani,Zeitschr. physikal. Chem., 1900,33. 469.[273]Reinders,Zeitschr. physikal. Chem., 1900,32. 494.[274]Hissink,Zeitschr. physikal. Chem., 1900,32. 542.[275]Van Eyk,Zeitschr. physikal. Chem., 1899,30. 430.[276]Cady,Journ. Physical. Chem., 1899,3. 127.[277]See Roberts-Austen and Stansfield,Rapports du congrès international de physique, 1900, I. 363.[278]Heycock and Neville,Proc. Roy. Soc., 1903,71. 409. For the partial liquefaction of mixed crystals on cooling, see also A. C. de Kock (Zeitschr. physikal. Chem., 1904,48. 129).[279]Armstrong,Watt's Dictionary of Chemistry(Morley and Muir), III., p. 88. See also Lowry,Jour. Chem. Soc., 1899,75. 211.[280]See Bancroft,Journ. Physical Chem., 1898,2. 143; Roozeboom,Zeitschr. physikal. Chem., 1899,28. 288.[281]Hylotropic substances are such as can undergo transformation into other substances of the same composition (Ostwald,Lehrbuch, II.2. 298).[282]Also called Equilibrium Point (Lowry).[283]For a discussion of these systems, see Roozeboom,Zeitschr. physikal. Chem.,loc. cit.[284]See Bancroft,loc. cit., p. 147; Wegscheider,Sitzungsber. Wiener Akad., 1902,110. 908.[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 (videAnnalen, 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, seeJourn. 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.[303]In this connection reference should be made more especially to the paper by Roberts-Austen and Stansfield, "Sur la constitution des alliages métalliques," in theRapports du congrès international de physique, 1900, I. 363; J. A. Mathews,Journ. of the Franklin Inst., 1902; Gautier,Compt. rend., 1896,123. 109; Roberts-Austen, "Reports of the Alloys Research Committee," inJourn. Inst. Mechan. Engineers, from 1891 to 1904; and the papers by Heycock and Neville, published in theJourn. Chem. Soc., and theTrans. Roy. Soc.since 1897; also Neville,Reports of the British Association, 1900, p. 131. Reference must also be made to the important metallographic investigations by Tammann and his pupils, and of Kurnakoff (Zeitschr. anorgan. Chem., vol.40and onwards), and also to those of Shepherd,Journ. Physical Chem.,8. A bibliography of the alloys is given inZeitschr. anorgan. Chem., 1903,35. 249.[304]Kurnakoff and Puschin,Zeitschr. anorgan. Chem., 1902,30. 104.[305]Gautier,Bull. Soc. d'Encouragement, 1896 [5],1. 1312.[306]Heycock and Neville,Phil. Trans., 1900,194. 201.[307]Gautier,loc. cit.See also Roberts-Austen and Rose,Proc. Roy. Soc., 1903,71. 161.[308]Heycock and Neville,Journ. Chem. Soc., 1897,71. 414.[309]See Roberts-Austen,Introduction to Metallurgy, 5th edit., p. 102; Bakhuis Roozeboom,Journ. Iron and Steel Inst., 1900, II. 311;Zeitschr. physikal. Chem., 1900,34. 437; von Jüptner,Siderology, p. 223 (translation by C. Salter); van't Hoff,Zinn, Gips, und Stahl, p. 24, orAcht Vorträge über physikalische Chemie, p. 37. Further, Roozeboom,Zeitschr. Elektrochem., 1904,10. 489; E. Heyn,ibid., p. 491; Carpenter and Keeling,Journ. Iron and Steel Inst., 1904,65. 224.[310]The melting point of pure iron is given by Carpenter and Keeling (Journ. Iron and Steel Inst., 1904,65. 224) as 1505°.[311]Zeitschr. für Elektrochem., 1904,10. 491.[312]See also Hiorns,Journ. Soc. Chem. Ind., 1906,25. 50.[313]Bancroft,Jour. Physical Chem., 1902,6. 178; Bell and Taber,ibid., 1906,10. 120.[314]The method to be followed when the third component enters into the solid phase will be explained later.[315]Tammann,Zeitschr. anorg. Chem., 1903,37. 303; 1905,45. 24. Reference may be made here to the registering pyrometer of Kurnakoff,Zeitschr. anorg. Chem., 1904,42. 184.[316]In this connection, see Doelter,Physikalisch-chemisch Mineralogie(Barth, 1901); Meyerhoffer,Zeitschr. f. Kristallographie, 1902,36. 593; Guthrie,Phil. Mag., 1884 [5],17. 479; Le Chatelier,Compt. rend., 1900,130. 85; and especially E. Baur,Zeitschr. physikal. Chem., 1903,42. 567; J. H. L. Vogt,Zeitschr. Elektrochem., 1903,9. 852, andDie Silikatschmelzlösungen, Parts I. and II. (Christiania, 1903, 1904). See also N. V. Kultascheff,Zeitschr. anorg. Chem., 1903,35. 187.[317]G. G. Stokes,Proc. Roy. Soc., 1891,49. 174; Gibbs,Trans. Conn. Acad., 1876,3. 176; Roozeboom,Zeitschr. physikal. Chem., 1894,15. 147.[318]This figure has been taken from Ostwald'sLehrbuch, II. 2. 984.[319]Roozeboom,Zeitschr. physikal. Chem., 1893,12. 369.[320]C. R. A. Wright,Proc. Roy. Soc., 1891,49. 174; 1892,50. 375.[321]The distribution coefficient will not remain constant because, apart from other reasons, the mutual solubility of chloroform and water is altered by the addition of the acid.[322]Bancroft,Physical Review, 1895,3. 21; Schreinemakers,Zeitschr. physikal. Chem., 1897,23. 652, and subsequent volumes.[323]C. R. A. Wright,Proc. Roy. Soc., 1889-1893.[324]C. R. A. Wright,Proc. Roy. Soc., 1892,50. 390.[325]Bodländer,Berg- und Hüttenmänn. Ztg., 1897,56. 331.[326]C. R. A. Wright,Proc. Roy. Soc.,loc. cit.[327]Schreinemakers,Zeitschr. physikal. Chem., 1900,33. 78.[328]Schreinemakers,Zeitschr. physikal. Chem., 1898,27. 95.[329]Schreinemakers,Zeitschr. physikal. Chem., 1899,29. 577.[330]Schreinemakers,Zeitschr. physikal. Chem., 1898,25. 543.[331]Charpy,Compt. rend., 1898,126. 1569. Compare the curves for the system KNO3—NaNO3—LiNO3(H. R. Carveth,Journ. Physical Chem., 1898,2. 209). Also alloys of Pb—Sn—Bi (E. S. Shepherd,Journ. Physical Chem., 1902,6. 527).[332]It should be remembered that in the triangular diagram alineparallel to one of the sides indicates, at a given temperature, a constant amount of the component represented by the opposite corner of the triangle; and, hence, points in aplane, parallel to one face of a right prism, will indicate for different temperatures, variation in the amounts of two components, but constancy in the amount of the third.[333]Gazzetta chim. ital., 1898,28. II. 520.[334]Bruni,Gazzetta chim. ital., 1898,28. II. 508; 1900,30. I. 35.[335]Zeitschr. physikal. Chem., 1900,36. 168.[336]For a discussion of these systems, see van't Hoff,Bildung und Spaltung von Doppelsalzen(Leipzig, 1897).[337]Van Leeuwen,Zeitschr. physikal. Chem., 1897,23. 35.[338]Meyerhoffer,Zeitschr. physikal. Chem., 1889,3. 336; 1890,5. 97.[339]Reicher,Zeitschr. physikal. Chem., 1887,1. 220.[340]For other examples of the formation and decomposition of double salts at a transition point, the reader is referred to the work by van't Hoff, already cited, on theBildung und Spaltung von Doppelsalzen; or to Bancroft,Phase Rule, p. 180.[341]Bancroft,Phase Rule, p. 183.[342]Roozeboom,Zeitschr. physikal. Chem., 1888,2. 514.[343]The influence of pressure on the transition point in the case of tachydrite has been determined by van't Hoff, Kenrick, and Dawson (Zeitschr. physikal. Chem., 1901,39. 27, 34; van't Hoff,Zur Bildung der ozeanischen Salzablagerungen, I. p. 66—Brunswick, 1905). This salt is formed from magnesium chloride and calcium chloride at 22°, in accordance with the equation—2MgCl2.6H2O + CaCl2.6H2O = Mg2CaCl6.12H2O + 6H2OIncrease of pressure raises the transition point, because the formation of tachydrite is accompanied by increase of volume; the elevation being 0.016° for an increase of pressure of 1 atm. The number calculated from the theoretical formula (p.57) is 0.013° for 1 atm.If one calculates the influence of the pressure of sea-water on the temperature of formation of tachydrite (which is of interest on account of the natural occurrence of this salt), it is found that a depth of water of 1500 metres, exerting a pressure of 180 atm., would alter the temperature of formation of tachydrite by only 3°. The effect is, therefore, comparatively unimportant.[344]Roozeboom,Zeitschr. physical. Chem., 1887,1. 227.[345]Zeitschr. physical. Chem., 1887,1. 227.[346]Van't Hoff and Müller,Ber., 1898,31. 2206.[347]Van't Hoff and van Deventer,Zeitschr. physikal. Chem., 1887,1. 165.[348]For a full discussion of the solubility relations of sodium ammonium racemate, see van't Hoff,Bildung und Spaltung von Doppelsalzen, p. 81.[349]Annales chim. phys., 1848 [3],24. 442.[350]See Van't Hoff and van Deventer,Zeitschr. phys. Chem., 1887,1. 165.[351]Meyerhoffer,Zeitschr. physikal. Chem., 1890,5. 121.[352]Roozeboom,Zeitschr. physikal. Chem., 1888,2. 518.[353]Meyerhoffer,Zeitschr. physikal. Chem., 1890,5. 109. On the importance of the transition interval in the case of optically active substances, see Meyerhoffer,Ber., 1904,37. 2604.[354]In connection with this chapter, see, more especially, van't Hoff,Bildung und Spaltung von Doppelsalzen, p. 3,ff.; Roozeboom,Zeitschr. physikal Chem., 1892,10. 158; Bancroft,Phase Rule, p. 201; 209.[355]The same restriction must be made here as was imposed in the preceding chapter, namely, that the two salts in solution give a common ion.[356]For example, addition of ammonium chloride to solutions of ferric chloride (Roozeboom,Zeitschr. physikal. Chem., 1892,10. 149).[357]It must, of course, be understood that the temperature is on that side of the transition point on which the double salt is stable.[358]Excess of the double salt must be taken, because otherwise an unsaturated solution might be formed, and this would, of course, not deposit any salt.[359]Meyerhoffer,Ber., 1904,37. 2605.[360]Meyerhoffer,Ber., 1897,30. 1809.[361]Meyerhoffer,Ber., 1904,37. 2604.[362]Bancroft,Phase Rule, p. 203; Roozeboom,Zeitschr. physikal. Chem., 1891,8. 504, 531; Stortenbeker,ibid., 1895,17. 643; 1897,22. 60; 1900,34. 108.[363]Roozeboom,Zeitschr. phys. Chem., 1899,28. 494;Ber., 1899,32. 537.[364]As, for instance, strychnine racemate, a compound of racemic acid with theoptically activestrychnine. This would be resolved into strychnined-tartrate and strychninel-tartrate, which are not enantiomorphous forms.[365]Van't Hoff and Meyerhoffer,Zeitschr. physikal Chem., 1898,27. 75; 1899,30. 86. Fig. 113 is taken from the latter paper.[366]Solid models constructed of plaster of Paris can be obtained from Max Kaehler and Martini, Berlin.[367]Instead of the present method of obtaining potassium chloride by decomposing carnallite with water, advantage might be taken of the fact that carnallite when heated to 168° undergoes decomposition with separation of three-fourths of the potassium chloride (van't Hoff,Acht Vorträge über physikalische Chemie, 1902, p. 32).[368]Roozeboom and Schreinemakers,Zeitschr. physikal. Chem., 1894,15. 588.[369]These curves represent only portions of the isotherms, since the systems in which a ternary solution is in equilibrium with solid hydrogen chloride or a hydrate, have not been investigated.[370]The numbers printed beside the points on the curves refer to the number of the experiment in the original paper.[371]Lash, Miller and Kenrick,Journ. Physical. Chem., 1903,7. 259; Allan,Amer. Chem. Journ., 1901,25. 307.[372]Allan,Amer. Chem. Journ., 1901,25. 307.[373]Hoitsema,Zeitschr. physikal. Chem., 1895,17. 651; Allan,loc. cit.[374]Rutten,Zeitschr. anorgan. Chem., 1902,30. 342. Compare the system BeO—SO3—H2O; Parsons,Zeitschr. anorgan. Chem., 1904,42. 250.[375]Zeitschr. anorgan. Chem., 1904,40. 146.[376]Schreinemakers,Zeitschr. physikal. Chem., 1893,11. 76; Bancroft,Journ. Physical Chem., 1902,6. 179.[377]Zeitschr. anorgan. Chem., 1904,40. 148.[378]Zeitschr. physikal. Chem., 1903,43. 354.[379]These equilibria were obtained by Boudouard,Annales chim. phys., 1901 [7],24. 5. See also Hahn,Zeitschr. physikal. Chem., 1903,42. 705;44. 513.[380]G. Preuner,Zeitschr. physikal. Chem., 1903,47. 385.[381]See Hahn,Zeitschr. physikal. Chem., 1903,42. 705;44. 513; Boudouard,Bull. Soc. chim., [3],25. 484; Bodländer,Zeitschr. f. Elektrochem., 1902,8. 833; R. Schenck and Zimmermann,Ber., 1903,36. 1231, 3663; Schenck and Heller,ibid., 1905,38. 2132;Zeitschr. f. Elektrochem., 1903,9. 691; Haber,Thermodynamik technischer Gasreaktionen, p. 293 (Munich, 1903).[382]A very useful summary of the investigations carried out by van't Hoff and his pupils on the formation of the Stassfurt salt-beds is given by E. F. Armstrong, in theReports of the British Association for 1901, p. 262. See also van't Hoff,Zur Bildung der ozeanischen Salzablagerungen(Brunswick, 1905).[383]See especially Meyerhoffer,Silzungsber. Wien. Akad., 1895,104. II.b, 840; Meyerhoffer and Saunders,Zeitschr. physikal. Chem., 1899,28. 453;31. 370. The investigation of the equilibria between reciprocal salt-pairs alone (three-component systems) is of great importance for the artificial preparations of minerals, as also in analytical chemistry for the proper understanding of the methods of conversion of insoluble systems into soluble by fusion (see Meyerhoffer,Zeitschr. physikal. Chem., 1901,38. 307).[384]See Meyerhoffer,Zeitschr. physikal. Chem., 1899,28. 459.[385]Compare the reciprocal salt-pair NaCl—NH4HCO3(p.321). In this case the upper limit of the transition interval was found by extrapolation of the solubility curve for NaHCO3+ NH4Cl + NH4HCO3and NaHCO3+ NH4Cl + NaCl to be 32° (Fedotieff,Zeitschr. phys. Chem., 1904,49. 179).[386]Löwenherz,Zeitschr. physikal. Chem., 1894,13. 464.[387]Meyerhoffer and Saunders,Zeitschr. physikal. Chem., 1899,28. 479.[388]As the quantities of the salts are expressed inequivalentgram-molecules, the molecule of sodium and potassium chloride must be doubled in order to be equivalent to sodium sulphate and potassium sulphate.[389]Sitz-Ber. der kgl. preuss. Akad. der Wiss., 1903, p. 359. Van't Hoff,Zur Bildung der ozeanischen Salzablagerungen, I. p. 34 (Brunswick, 1905).[390]Zeitschr. für Kristallographie, 1904,39. 155.[391]Meyerhoffer and Saunders,Zeitschr. physikal. Chem., 1899,28. 479.[392]Zeitschr. physikal. Chem., 1904,49. 162.[393]Another commercial process, in the study of which good service is done by the Phase Rule, is the caustification of the alkali salts (G. Bodländer,Zeitschr. für Elektrochem., 1905,11. 186; J. Herold,ibid., 418).[394]Zeitschr. physikal. Chem., 1900,35. 32.[395]Mention may also be made here of the equilibria between magnesium carbonate and potassium carbonate, although these do not form a reciprocal salt-pair (Auerbach,Zeitschr. für Elektrochem., 1904,10. 161).[396]O. N. Witt and K. Ludwig,Ber., 1903,36. 4384; Meyerhoffer,ibid., 1904,37. 261, 1116.[397]Zeitschr. physikal. Chem., 1905,53. 513. Compare also,ibid., 1903,38. 307.[398]See Schwarz,Beiträge zur Kenntnis der umkehrbaren Umwandlungen polymorpher Korper(Göttingen, 1892); or, Roozeboom,Heterogen. Gleichgewicht, I. p. 125. Also Barnes and Cooke,Journ. Physical Chem., 1902,6. 172.[399]Van't Hoff and van Deventer,Zeitschr. physikal. Chem., 1887,1. 173.[400]Reicher,Zeitschr. für Krystallographie, 1884,8. 593.[401]Zeitschr. physikal. Chem., 1895,17. 153.[402]Zeitschr. physikal. Chem., 1899,28. 464.[403]Meyerhoffer and Saunders,ibid., p. 466.[404]See Van Eyk,Zeitschr. physikal. Chem., 1899,30. 446.[405]See in this connection the volume in this series onElectro-chemistry, by Dr. R. A. Lehfeldt.[406]Barnes and Cooke,Journ. Physical Chem., 1902,6. 172.[407]For a description and explanation of these, the reader should consult the volume in this series by Dr. Lehfeldt onElectro-chemistry; and van't Hoff,Bildung und Spaltung von Doppelsalzen, p. 48ff.
[272]Adriani,Zeitschr. physikal. Chem., 1900,33. 469.
[273]Reinders,Zeitschr. physikal. Chem., 1900,32. 494.
[274]Hissink,Zeitschr. physikal. Chem., 1900,32. 542.
[275]Van Eyk,Zeitschr. physikal. Chem., 1899,30. 430.
[276]Cady,Journ. Physical. Chem., 1899,3. 127.
[277]See Roberts-Austen and Stansfield,Rapports du congrès international de physique, 1900, I. 363.
[278]Heycock and Neville,Proc. Roy. Soc., 1903,71. 409. For the partial liquefaction of mixed crystals on cooling, see also A. C. de Kock (Zeitschr. physikal. Chem., 1904,48. 129).
[279]Armstrong,Watt's Dictionary of Chemistry(Morley and Muir), III., p. 88. See also Lowry,Jour. Chem. Soc., 1899,75. 211.
[280]See Bancroft,Journ. Physical Chem., 1898,2. 143; Roozeboom,Zeitschr. physikal. Chem., 1899,28. 288.
[281]Hylotropic substances are such as can undergo transformation into other substances of the same composition (Ostwald,Lehrbuch, II.2. 298).
[282]Also called Equilibrium Point (Lowry).
[283]For a discussion of these systems, see Roozeboom,Zeitschr. physikal. Chem.,loc. cit.
[284]See Bancroft,loc. cit., p. 147; Wegscheider,Sitzungsber. Wiener Akad., 1902,110. 908.
[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 (videAnnalen, 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, seeJourn. 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.
[303]In this connection reference should be made more especially to the paper by Roberts-Austen and Stansfield, "Sur la constitution des alliages métalliques," in theRapports du congrès international de physique, 1900, I. 363; J. A. Mathews,Journ. of the Franklin Inst., 1902; Gautier,Compt. rend., 1896,123. 109; Roberts-Austen, "Reports of the Alloys Research Committee," inJourn. Inst. Mechan. Engineers, from 1891 to 1904; and the papers by Heycock and Neville, published in theJourn. Chem. Soc., and theTrans. Roy. Soc.since 1897; also Neville,Reports of the British Association, 1900, p. 131. Reference must also be made to the important metallographic investigations by Tammann and his pupils, and of Kurnakoff (Zeitschr. anorgan. Chem., vol.40and onwards), and also to those of Shepherd,Journ. Physical Chem.,8. A bibliography of the alloys is given inZeitschr. anorgan. Chem., 1903,35. 249.
[304]Kurnakoff and Puschin,Zeitschr. anorgan. Chem., 1902,30. 104.
[305]Gautier,Bull. Soc. d'Encouragement, 1896 [5],1. 1312.
[306]Heycock and Neville,Phil. Trans., 1900,194. 201.
[307]Gautier,loc. cit.See also Roberts-Austen and Rose,Proc. Roy. Soc., 1903,71. 161.
[308]Heycock and Neville,Journ. Chem. Soc., 1897,71. 414.
[309]See Roberts-Austen,Introduction to Metallurgy, 5th edit., p. 102; Bakhuis Roozeboom,Journ. Iron and Steel Inst., 1900, II. 311;Zeitschr. physikal. Chem., 1900,34. 437; von Jüptner,Siderology, p. 223 (translation by C. Salter); van't Hoff,Zinn, Gips, und Stahl, p. 24, orAcht Vorträge über physikalische Chemie, p. 37. Further, Roozeboom,Zeitschr. Elektrochem., 1904,10. 489; E. Heyn,ibid., p. 491; Carpenter and Keeling,Journ. Iron and Steel Inst., 1904,65. 224.
[310]The melting point of pure iron is given by Carpenter and Keeling (Journ. Iron and Steel Inst., 1904,65. 224) as 1505°.
[311]Zeitschr. für Elektrochem., 1904,10. 491.
[312]See also Hiorns,Journ. Soc. Chem. Ind., 1906,25. 50.
[313]Bancroft,Jour. Physical Chem., 1902,6. 178; Bell and Taber,ibid., 1906,10. 120.
[314]The method to be followed when the third component enters into the solid phase will be explained later.
[315]Tammann,Zeitschr. anorg. Chem., 1903,37. 303; 1905,45. 24. Reference may be made here to the registering pyrometer of Kurnakoff,Zeitschr. anorg. Chem., 1904,42. 184.
[316]In this connection, see Doelter,Physikalisch-chemisch Mineralogie(Barth, 1901); Meyerhoffer,Zeitschr. f. Kristallographie, 1902,36. 593; Guthrie,Phil. Mag., 1884 [5],17. 479; Le Chatelier,Compt. rend., 1900,130. 85; and especially E. Baur,Zeitschr. physikal. Chem., 1903,42. 567; J. H. L. Vogt,Zeitschr. Elektrochem., 1903,9. 852, andDie Silikatschmelzlösungen, Parts I. and II. (Christiania, 1903, 1904). See also N. V. Kultascheff,Zeitschr. anorg. Chem., 1903,35. 187.
[317]G. G. Stokes,Proc. Roy. Soc., 1891,49. 174; Gibbs,Trans. Conn. Acad., 1876,3. 176; Roozeboom,Zeitschr. physikal. Chem., 1894,15. 147.
[318]This figure has been taken from Ostwald'sLehrbuch, II. 2. 984.
[319]Roozeboom,Zeitschr. physikal. Chem., 1893,12. 369.
[320]C. R. A. Wright,Proc. Roy. Soc., 1891,49. 174; 1892,50. 375.
[321]The distribution coefficient will not remain constant because, apart from other reasons, the mutual solubility of chloroform and water is altered by the addition of the acid.
[322]Bancroft,Physical Review, 1895,3. 21; Schreinemakers,Zeitschr. physikal. Chem., 1897,23. 652, and subsequent volumes.
[323]C. R. A. Wright,Proc. Roy. Soc., 1889-1893.
[324]C. R. A. Wright,Proc. Roy. Soc., 1892,50. 390.
[325]Bodländer,Berg- und Hüttenmänn. Ztg., 1897,56. 331.
[326]C. R. A. Wright,Proc. Roy. Soc.,loc. cit.
[327]Schreinemakers,Zeitschr. physikal. Chem., 1900,33. 78.
[328]Schreinemakers,Zeitschr. physikal. Chem., 1898,27. 95.
[329]Schreinemakers,Zeitschr. physikal. Chem., 1899,29. 577.
[330]Schreinemakers,Zeitschr. physikal. Chem., 1898,25. 543.
[331]Charpy,Compt. rend., 1898,126. 1569. Compare the curves for the system KNO3—NaNO3—LiNO3(H. R. Carveth,Journ. Physical Chem., 1898,2. 209). Also alloys of Pb—Sn—Bi (E. S. Shepherd,Journ. Physical Chem., 1902,6. 527).
[332]It should be remembered that in the triangular diagram alineparallel to one of the sides indicates, at a given temperature, a constant amount of the component represented by the opposite corner of the triangle; and, hence, points in aplane, parallel to one face of a right prism, will indicate for different temperatures, variation in the amounts of two components, but constancy in the amount of the third.
[333]Gazzetta chim. ital., 1898,28. II. 520.
[334]Bruni,Gazzetta chim. ital., 1898,28. II. 508; 1900,30. I. 35.
[335]Zeitschr. physikal. Chem., 1900,36. 168.
[336]For a discussion of these systems, see van't Hoff,Bildung und Spaltung von Doppelsalzen(Leipzig, 1897).
[337]Van Leeuwen,Zeitschr. physikal. Chem., 1897,23. 35.
[338]Meyerhoffer,Zeitschr. physikal. Chem., 1889,3. 336; 1890,5. 97.
[339]Reicher,Zeitschr. physikal. Chem., 1887,1. 220.
[340]For other examples of the formation and decomposition of double salts at a transition point, the reader is referred to the work by van't Hoff, already cited, on theBildung und Spaltung von Doppelsalzen; or to Bancroft,Phase Rule, p. 180.
[341]Bancroft,Phase Rule, p. 183.
[342]Roozeboom,Zeitschr. physikal. Chem., 1888,2. 514.
[343]The influence of pressure on the transition point in the case of tachydrite has been determined by van't Hoff, Kenrick, and Dawson (Zeitschr. physikal. Chem., 1901,39. 27, 34; van't Hoff,Zur Bildung der ozeanischen Salzablagerungen, I. p. 66—Brunswick, 1905). This salt is formed from magnesium chloride and calcium chloride at 22°, in accordance with the equation—
2MgCl2.6H2O + CaCl2.6H2O = Mg2CaCl6.12H2O + 6H2O
Increase of pressure raises the transition point, because the formation of tachydrite is accompanied by increase of volume; the elevation being 0.016° for an increase of pressure of 1 atm. The number calculated from the theoretical formula (p.57) is 0.013° for 1 atm.
If one calculates the influence of the pressure of sea-water on the temperature of formation of tachydrite (which is of interest on account of the natural occurrence of this salt), it is found that a depth of water of 1500 metres, exerting a pressure of 180 atm., would alter the temperature of formation of tachydrite by only 3°. The effect is, therefore, comparatively unimportant.
[344]Roozeboom,Zeitschr. physical. Chem., 1887,1. 227.
[345]Zeitschr. physical. Chem., 1887,1. 227.
[346]Van't Hoff and Müller,Ber., 1898,31. 2206.
[347]Van't Hoff and van Deventer,Zeitschr. physikal. Chem., 1887,1. 165.
[348]For a full discussion of the solubility relations of sodium ammonium racemate, see van't Hoff,Bildung und Spaltung von Doppelsalzen, p. 81.
[349]Annales chim. phys., 1848 [3],24. 442.
[350]See Van't Hoff and van Deventer,Zeitschr. phys. Chem., 1887,1. 165.
[351]Meyerhoffer,Zeitschr. physikal. Chem., 1890,5. 121.
[352]Roozeboom,Zeitschr. physikal. Chem., 1888,2. 518.
[353]Meyerhoffer,Zeitschr. physikal. Chem., 1890,5. 109. On the importance of the transition interval in the case of optically active substances, see Meyerhoffer,Ber., 1904,37. 2604.
[354]In connection with this chapter, see, more especially, van't Hoff,Bildung und Spaltung von Doppelsalzen, p. 3,ff.; Roozeboom,Zeitschr. physikal Chem., 1892,10. 158; Bancroft,Phase Rule, p. 201; 209.
[355]The same restriction must be made here as was imposed in the preceding chapter, namely, that the two salts in solution give a common ion.
[356]For example, addition of ammonium chloride to solutions of ferric chloride (Roozeboom,Zeitschr. physikal. Chem., 1892,10. 149).
[357]It must, of course, be understood that the temperature is on that side of the transition point on which the double salt is stable.
[358]Excess of the double salt must be taken, because otherwise an unsaturated solution might be formed, and this would, of course, not deposit any salt.
[359]Meyerhoffer,Ber., 1904,37. 2605.
[360]Meyerhoffer,Ber., 1897,30. 1809.
[361]Meyerhoffer,Ber., 1904,37. 2604.
[362]Bancroft,Phase Rule, p. 203; Roozeboom,Zeitschr. physikal. Chem., 1891,8. 504, 531; Stortenbeker,ibid., 1895,17. 643; 1897,22. 60; 1900,34. 108.
[363]Roozeboom,Zeitschr. phys. Chem., 1899,28. 494;Ber., 1899,32. 537.
[364]As, for instance, strychnine racemate, a compound of racemic acid with theoptically activestrychnine. This would be resolved into strychnined-tartrate and strychninel-tartrate, which are not enantiomorphous forms.
[365]Van't Hoff and Meyerhoffer,Zeitschr. physikal Chem., 1898,27. 75; 1899,30. 86. Fig. 113 is taken from the latter paper.
[366]Solid models constructed of plaster of Paris can be obtained from Max Kaehler and Martini, Berlin.
[367]Instead of the present method of obtaining potassium chloride by decomposing carnallite with water, advantage might be taken of the fact that carnallite when heated to 168° undergoes decomposition with separation of three-fourths of the potassium chloride (van't Hoff,Acht Vorträge über physikalische Chemie, 1902, p. 32).
[368]Roozeboom and Schreinemakers,Zeitschr. physikal. Chem., 1894,15. 588.
[369]These curves represent only portions of the isotherms, since the systems in which a ternary solution is in equilibrium with solid hydrogen chloride or a hydrate, have not been investigated.
[370]The numbers printed beside the points on the curves refer to the number of the experiment in the original paper.
[371]Lash, Miller and Kenrick,Journ. Physical. Chem., 1903,7. 259; Allan,Amer. Chem. Journ., 1901,25. 307.
[372]Allan,Amer. Chem. Journ., 1901,25. 307.
[373]Hoitsema,Zeitschr. physikal. Chem., 1895,17. 651; Allan,loc. cit.
[374]Rutten,Zeitschr. anorgan. Chem., 1902,30. 342. Compare the system BeO—SO3—H2O; Parsons,Zeitschr. anorgan. Chem., 1904,42. 250.
[375]Zeitschr. anorgan. Chem., 1904,40. 146.
[376]Schreinemakers,Zeitschr. physikal. Chem., 1893,11. 76; Bancroft,Journ. Physical Chem., 1902,6. 179.
[377]Zeitschr. anorgan. Chem., 1904,40. 148.
[378]Zeitschr. physikal. Chem., 1903,43. 354.
[379]These equilibria were obtained by Boudouard,Annales chim. phys., 1901 [7],24. 5. See also Hahn,Zeitschr. physikal. Chem., 1903,42. 705;44. 513.
[380]G. Preuner,Zeitschr. physikal. Chem., 1903,47. 385.
[381]See Hahn,Zeitschr. physikal. Chem., 1903,42. 705;44. 513; Boudouard,Bull. Soc. chim., [3],25. 484; Bodländer,Zeitschr. f. Elektrochem., 1902,8. 833; R. Schenck and Zimmermann,Ber., 1903,36. 1231, 3663; Schenck and Heller,ibid., 1905,38. 2132;Zeitschr. f. Elektrochem., 1903,9. 691; Haber,Thermodynamik technischer Gasreaktionen, p. 293 (Munich, 1903).
[382]A very useful summary of the investigations carried out by van't Hoff and his pupils on the formation of the Stassfurt salt-beds is given by E. F. Armstrong, in theReports of the British Association for 1901, p. 262. See also van't Hoff,Zur Bildung der ozeanischen Salzablagerungen(Brunswick, 1905).
[383]See especially Meyerhoffer,Silzungsber. Wien. Akad., 1895,104. II.b, 840; Meyerhoffer and Saunders,Zeitschr. physikal. Chem., 1899,28. 453;31. 370. The investigation of the equilibria between reciprocal salt-pairs alone (three-component systems) is of great importance for the artificial preparations of minerals, as also in analytical chemistry for the proper understanding of the methods of conversion of insoluble systems into soluble by fusion (see Meyerhoffer,Zeitschr. physikal. Chem., 1901,38. 307).
[384]See Meyerhoffer,Zeitschr. physikal. Chem., 1899,28. 459.
[385]Compare the reciprocal salt-pair NaCl—NH4HCO3(p.321). In this case the upper limit of the transition interval was found by extrapolation of the solubility curve for NaHCO3+ NH4Cl + NH4HCO3and NaHCO3+ NH4Cl + NaCl to be 32° (Fedotieff,Zeitschr. phys. Chem., 1904,49. 179).
[386]Löwenherz,Zeitschr. physikal. Chem., 1894,13. 464.
[387]Meyerhoffer and Saunders,Zeitschr. physikal. Chem., 1899,28. 479.
[388]As the quantities of the salts are expressed inequivalentgram-molecules, the molecule of sodium and potassium chloride must be doubled in order to be equivalent to sodium sulphate and potassium sulphate.
[389]Sitz-Ber. der kgl. preuss. Akad. der Wiss., 1903, p. 359. Van't Hoff,Zur Bildung der ozeanischen Salzablagerungen, I. p. 34 (Brunswick, 1905).
[390]Zeitschr. für Kristallographie, 1904,39. 155.
[391]Meyerhoffer and Saunders,Zeitschr. physikal. Chem., 1899,28. 479.
[392]Zeitschr. physikal. Chem., 1904,49. 162.
[393]Another commercial process, in the study of which good service is done by the Phase Rule, is the caustification of the alkali salts (G. Bodländer,Zeitschr. für Elektrochem., 1905,11. 186; J. Herold,ibid., 418).
[394]Zeitschr. physikal. Chem., 1900,35. 32.
[395]Mention may also be made here of the equilibria between magnesium carbonate and potassium carbonate, although these do not form a reciprocal salt-pair (Auerbach,Zeitschr. für Elektrochem., 1904,10. 161).
[396]O. N. Witt and K. Ludwig,Ber., 1903,36. 4384; Meyerhoffer,ibid., 1904,37. 261, 1116.
[397]Zeitschr. physikal. Chem., 1905,53. 513. Compare also,ibid., 1903,38. 307.
[398]See Schwarz,Beiträge zur Kenntnis der umkehrbaren Umwandlungen polymorpher Korper(Göttingen, 1892); or, Roozeboom,Heterogen. Gleichgewicht, I. p. 125. Also Barnes and Cooke,Journ. Physical Chem., 1902,6. 172.
[399]Van't Hoff and van Deventer,Zeitschr. physikal. Chem., 1887,1. 173.
[400]Reicher,Zeitschr. für Krystallographie, 1884,8. 593.
[401]Zeitschr. physikal. Chem., 1895,17. 153.
[402]Zeitschr. physikal. Chem., 1899,28. 464.
[403]Meyerhoffer and Saunders,ibid., p. 466.
[404]See Van Eyk,Zeitschr. physikal. Chem., 1899,30. 446.
[405]See in this connection the volume in this series onElectro-chemistry, by Dr. R. A. Lehfeldt.
[406]Barnes and Cooke,Journ. Physical Chem., 1902,6. 172.
[407]For a description and explanation of these, the reader should consult the volume in this series by Dr. Lehfeldt onElectro-chemistry; and van't Hoff,Bildung und Spaltung von Doppelsalzen, p. 48ff.