Excerpt from On the Adaptation of External Nature to the Physical Condition of Man, Principally With Reference to the Supply of His Wants, and the Exercise of His Intellectual Faculties In the mineral kingdom the most characteristic property of the se veral species appears to be a disposition to a pecular mode of mutual attraction among the particles composing the individuals belonging to them; from which attraction, when exerted under the most favour able circumstances, result that symmetry and regularity of form, to which the term crystal has been applied. The transparency and degree of hardness of crystals are various, and depend much upon external circumstances. The form is fundamentally the same for each species, though capable of being modified according to known laws; and the substance is chemically the same throughout its whole extent. Every atom of a crystallized mass of gypsum consists of water, lime, and sulphuric acid, united in the same proportions as are found to exist in the whole mass, or in any given part of it. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.