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On the regular growth of soluble salts on each other

Published online by Cambridge University Press:  14 March 2018

Thomas Vipond Barker*
Affiliation:
Magdalen College, Oxford

Extract

Previous work on the regular growth of crystals of salts on those of Minerals belonging to the same isostructural series led the author to the discovery that parallel deposition is conditioned by closeness, not of angle nor of axial ratios, but of molecular volume. Now although the substances previously examined resemble each other crystallographically, yet they exhibit such great differences in chemical properties, that reasonable doubt might be entertained whether conclusions drawn from them can be directly applied to isomorphous substances ; and it therefore became advisable to extend the observations to a group of the latter.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1907

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References

Page 235 note 1 Barker, T. V., ‘Contributions to the theory of isomorphism based on experiments on the regular growths of crystals of one substance on those of another.’ Journ Chem. Soc. Trans., 1906, vol. lxxxix, pp. 11201158 CrossRefGoogle Scholar.

Page 237 note 1 Ann. Chim. Phys. 1882, ser. 5, vol. xxvi, p. 484.

Page 238 note 1 Zeits. physik. Chem., 1892, vol. ix, p. 267.

Page 238 note 2 Zeits. physik. Chem., 1896, vol. xxi, p. 71

Page 238 note 3 Neues Jahrb. Min., 1904, Beilage-Band xvi, p. 121.

Page 239 note 1 Gossner, Zeits. Kryst. Min., 1903, vol. xl, p. 70.

Page 239 note 2 Favre and Valson, Compt. rend. Acad. Sci. Paris, 1873, vol. lxxvii, p. 579.

Page 239 note 3 Sprockhoff, loc. cit.

Page 239 note 4 Slavík, Zeits. Kryst. Min., 1902, vol. xxxvi, p. 271.

Page 239 note 5 Öfrets. k. Vet.-Akad. Förh. Stockholm, 1882, vol. vi, p. 23.

Page 240 note 1 The term irregular does not mean that the outlines of the crystal were ill-defined, nor does it mean that the crystals do not belong to the regular system ; throughout this paper it is consistently used to denote not parallel.

Page 245 note 1 It is worthy of note that the difference in molecular volume of the sodium and potassium salts is about twice the corresponding difference between the potassium and rubidium salts, and it may possibly be argued from this that the sodium salts ought to form a further sub-section of group A ; still another argument in favour of this is found in the total non-miscibility of sodium chloride and potassium chloride (Kriekmeyer, loc cit.). On the other hand, since the molecular volumes of the sodium salts are so low, it might be inferred that they ought to belong to group B ; but, as will be seen later, the good cubic cleavage and, more especially, the experiments on parallel growth effectually negative this alternative.

Page 247 note 1 Zeits. Kryst. Min., 1905, vol. xl, p. 69.

Page 247 note 2 Zeits. Kryst. Min., 1897, vol. xxviii, p. 351.

Page 247 note 3 The symmetry of a crystal, as derived from etching figures, does not necessarily give the real symmetry ; for the latter, although it cannot be higher, may nevertheless be lower than the former. Hence, it is not absolutely excluded that the real symmetry of the above compounds is the same. and possibly even lower than the symmetry exemplified by the tesseral-holoaxial class.

Page 248 note 1 Zeits. Kryst. Min., 1885, vol. x, p. 321.

Page 256 note 1 The values of the valency volumes were derived from the following considerations. Barlow and Pope take S and O as divalent ; N, trivalent ; and H, CI, K, Rb, Cs, and TI monovalent. The writer considers that Ba, Pb, and Sr must be divalent, and has deduced the valency volumes of the permanganates and percldorates from that of the sulphates by Barlow and Pope's second principle: the replacement of Ba by K necessarily requires a decrease by one in the valency volume of the remaining complex. The valency volume of KMnO4, is therefore 10, and this agrees with the valency volume of KCIO4 which must necessarily be 10 since Cl is monovalent. If manganese be taken as divalent (KMnO4 = 11 ), resuits are obtained in the equivalence parameters which are at a still greater variance than in the given table.