An introduction to mineralogy : comprising the natural history and characters of minerals; and a description of rocks, both simple and aggregated; with a new tabular arrangement of earthy minerals, on a plan designed to facilitate the knowledge of that class of substances. To which is prefixed: a series of conversations explaining the principles of the science, and the elements of crystallography / By Robert Bakewell, author of "An introduction to Geology." With plates.

  • Bakewell, Robert, 1768-1843.
Date:
1819
Catalogue details

Licence: Public Domain Mark

Credit: An introduction to mineralogy : comprising the natural history and characters of minerals; and a description of rocks, both simple and aggregated; with a new tabular arrangement of earthy minerals, on a plan designed to facilitate the knowledge of that class of substances. To which is prefixed: a series of conversations explaining the principles of the science, and the elements of crystallography / By Robert Bakewell, author of "An introduction to Geology." With plates. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    30/712 (page 4)
    B. The diliereiice wliicli strikes you moat forcibly is principally the opacity of the quartz ; were they both pulverised, they would form a white opaque powder, possessing precisely the same properties. F. I have seen the crystallization of salts from saline solutions, is the rock-crystal formed by a similar process ? B. Rock crystals were the first crystallized substances that the ancients appear to have noticed j they supposed that rock-crystal was water permanently congealed ; hence the word crystal ^is derived from the Greek KriistalloSy which signifies ice. In chemistry and the arts, the effects of crystallization are the same as in the mineral kingdom. Sugar-candy is crystal- lized sugar, and differs in appearance as much from raw sugar, as rock-crystal does from opaque quartz. Sugar becomes transparent by crystallization, and you know that alum, salt- petre, and common salt, when crystallized, take certain forms peculiar to each. Crystals of common salt are cubical, those of alum are octahedrons, and those of salt-petre six-sided prisms. The rock-crystal you have in your hand is a six-sided prism terminated by a six- sided pyramid, which is its most common form. Now we may infer from this similarity of effects, that the process of crystallization in all these substances, depends on one general law, modi- fied by the nature of each.