On certain laws of cohesive attraction / By James D. Dana.

  • Dana, James Dwight, 1813-1895.
Date:
1847]
Catalogue details

Licence: Public Domain Mark

Credit: On certain laws of cohesive attraction / By James D. Dana. Source: Wellcome Collection.

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    ON CERTAIN LAWS OF COHESIVE ATTRACTION. BY JAMES D. DANA. Read before the American Association of Geologists and Naturalists, held at Boston, September, 1847. From the account of cohesive attraction in works on Chem¬ istry, we gather little more than what the term itself implies ; and in the higher treatises on Physics, the subject is discussed on general mathematical principles, and mostly without reference to observed facts, excepting those of the most obvious character. This is especially true of the attraction in solidification. I propose to consider what observation teaches on this subject, and would ask the attention of the Association to a brief statement of a series of facts, and to certain obvious inferences from these facts. The objects to which we appeal for illustration, are the rocks and minerals of the earth, and the ordinary forms of inorganic matter. The grand principle has already been recognized, that solidification and crystallization are the same process. As early as 1807, in the Lectures on Natural Philosophy by the learned Thomas Young,* this philosopher says, after some explanatory remarks, “ It appears, therefore, consistent both with reason and experience, to suppose that a crystallization more or less perfect is the universal cause of solidity.” Biot in his Precisf recognizes the same principle; and other names favoring this conclusion might be mentioned. The fact is obviously exemplified in nearly every inorganic solid around us. The freezing of water is known to be its crystallization, and snow is crystallized vapor. The coarse-grained structure of bar-iron is correctly called its crystal¬ line structure: for the grains are all formed by the process of crystallization; and in steel we perceive the same texture, and may trace it through varieties, till the grains are too fine to be distinguished. Granite and all igneous rocks are made up of * Course of Lectures on Natural Philosophy and the Mechanical Arts, by Thomas Young, M.D., 2 vols. 4to. London, 1807. Vol. i, p. 628. t Pr6cis Elementaire de Physique, 2 vols. 8vo. Paris, 1824. Vol. i, p. 18. Am. Jour. Sci., 2d Ser., Vol. IV.—Nov. 1847. 1