The object of this paper was the refutation of certain arguments brought forward against the doctrine of Isomorphism, more especially by those who allow the existence of an approach to, although they deny absolute identity of, form.

The author sets out by shewing, that most of the arguments are deduced from observations made on crystallized minerals; and he then proceeds to state the many important circumstances which tend to influence the form of these bodies, but which can be easily avoided in those salts which admit of being formed artificially; such are, the intense temperature to which they are subjected, the pressure of surrounding matter, the admixture of foreign bodies, &c. each and all of which he proves to exert a powerful influence over the forms of crystals.