Isomorphism and Homology

Abstract

IT is well known that the law of iso-morphism discovered by Mitscherlich is now accepted with considerable limitations. Marignac, for example, showed long ago that the compounds ZnTiF₆, 6H₂O, ZnCbOF₅,6H₂O, ZnWO₂F₄,6H₂O, though homomorphous and capable of forming mixed crystals, are not identical in chemical formulæ. It is to be assumed that there are not only homologous elements but also homologous radicals. The ability to form mixed crystals, homomorphism, and identity of chemical formulæ are not necessarily co-existent. But when certain elements or radicals can be substituted totally or partially in very different salts, the analogy of these elements or radicals remains undisputable and makes legitimate the parallelism of chemical formulæ.