An introduction to chemical crystallography / by P. Groth, Authorised translation by Hugh Marshall.

  • Groth, P. (Paul), 1843-1927.
Date:
1906
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to chemical crystallography / by P. Groth, Authorised translation by Hugh Marshall. Source: Wellcome Collection.

    90/144 (page 74)
    the question of the isomorphous replacement of these two metals requires further investigation. II. Group of the bivalent metals.—Beryllium, in agreement with magnesium and zinc, crystallises hexagonal, and further, the form of beryllium oxide exhibits certain analogies with that of zinc oxide ; nevertheless an isomorphous replacement of beryllium by other bivalent metals in analogous salts has been found only in few cases. Beryllium aluminate and chromite, Be(A102)2 and Be(Cr02)2, crystallise differently from the magnesium salts, Mg(A102)2 and Mg(Cr02)2, whilst the double phosphates, NaBeP04 and NaMnP04, exhibit very similar forms. In some other phosphates, as, for example, the mineral groups of wagnerite, MgMgFP04, and herderite, CaBeFP04, more intimate relations between beryllium and the other bivalent metals may be recognised. Among the silicates, only phenacite, Be2Si04, and willemite, Zn2Si04, are comparable, because the salts of other metals, corresponding in composition to the remaining beryllium silicates (and therefore potentially isomorphous with them) are unknown. Further, there exist no normal beryllium salts of the fatty acids. Very many groups of analogously constituted salts of the bivalent metals magnesium, manganese, iron, nickel, cobalt, zinc, and cadmium, derived from the most various acids, organic as well as inorganic, have been crystallographically determined; with these it is regularly found that there is a very complete isomorphism of all the members of any such group. The same applies to the hydroxides, and also, to a certain extent, to the elements themselves. In the few cases in which apparent ex¬ ceptions to this rule are found, as with magnesium sulphate and ferrous sulphate, it can be shown beyond doubt that the respective salts are isodimorphous (see under “ Isomorphous Mixtures,” page 91). Bivalent copper in the simpler compounds appears to stand apart from the above-mentioned metals, but in more complex salts it takes its place beside them ; thus the fluosilicate, CuSiF6,6H20, is isomorphous with the corresponding salts of magnesium, manganese, iron, nickel, cobalt and zinc ; also the fluozirconate, Cu2ZrF8,T2FLO, with that of zinc; the sulphate, CuS04,5H20, and double sulphate, K2Cu(S04)2,6H20, with those of magnesium, manganese, iron, cobalt, zinc, and cadmium ; but whilst the double sulphates of the other metals agree very closely among themselves as regards their angles, the copper salt in this respect stands distinctly apart. Further examples are supplied