Volume 1

A system of chemistry ... / [John Murray].

  • John Murray
Date:
1806-1807
Catalogue details

Licence: Public Domain Mark

Credit: A system of chemistry ... / [John Murray]. Source: Wellcome Collection.

    78/756 page 56
    » 56 OF THE ATTRACTION primitive form; and the only limit to this possible division, is that placed by the composition of the sub- stance, The calcareous spar, to take it as an example, may be reduced to a particle, beyond which the di- vision cannot be carried, without resolving it into its elements, lime and-carbonic acid ; or, at least, it may be reduced to a particle, beyond which, if its minute- ness allowed us to operate upon it, it is demonstrable its figure would not change. To these last particles, the result of the mechanical analysis, Hauy gives the name of zategrant particles, and their union consti- tutes the crystal. Their forms, so far as experiment has been carried, are three: the tetraedron, the sim- plest of pyramids; the triangular prism, the simplest of prisms; and the parallelopipedon, the simplest of solids which have their faces parallel two and two. There can be little doubt, that it is between these that the attraction of cohesion is immediately exerted, The primitive forms and the figures of the inte- grant particles being determined, it remains, to com- plete the theory of the structure of crystals, to shew by what arrangements the secondary forms, in other words, the actually existing crystals, are produced. The nucleus of the crystal 1s the symmetrical solid which constitutes its primitive form, arising from the _ union of the integrant particles, either by their faces or their edges; and the additional matter which forms the crystal consists of layers of these particles, super- added to that nucleus, and arranged on its faces; and to account for the formation of the crystal under a figure different from that of its primitive form, these
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