Page:Popular Science Monthly Volume 37.djvu/428

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compilation of trustworthy patent-lists. Volume I goes from A to Dy. Among its chief articles are those on acetic acid, alcohol, alizarin and allied coloring matters, aluminium, ammonia, analysis, azo-coloring matters, bleaching, brewing, carbon, cements, chlorine, cyanides, dextrose, disinfectants, and dyeing. Under alizarin are given the history of the artificial production of this substance, the methods of preparing a large number of derivatives of anthraquinone, and accounts of the anthraquinone and dichloranthracene processes of manufacturing alizarin. The article on brewing comprises quite full consideration of the sources and chemical character of the water, barley, and hops used in making beer, with descriptions of the several steps in the process. Sixteen figures of brewing apparatus are given. In the article on cements, both building cements and adhesive cements are treated. Under the former division are included lime-burning, mortar, plaster of Paris, hydraulic mortar, pozzuolana, hydraulic cement, oxychloride cements, artificial stone, and concrete. Analyses of many of these substances are given in tables, and a bibliography of the subject is appended. Many of the articles involving descriptions of apparatus are fully illustrated. The more important ones are signed, and a list of contributors to the volume is prefixed, among which may be found many well-known names.

Gems and Precious Stones of North America. By George Frederick Kunz. Illustrated with Eight Colored Plates and numerous Minor Engravings. New York: The Scientific Publishing Company. Pp. 336. Large 8vo. Price, $10.

Mr. Kunz has written a very interesting book, and it has been published in an elegant style. Nearly all the known varieties of precious stones occur in North America, and many of the American specimens have much beauty, but they are not found of such size and quality nor in sufficient quantity to rank them as an important product of the country. About one hundred thousand dollars' worth of precious stones, including pearls, are found in the United States yearly, but this is less than the value of the output from the diamond-mines of South Africa, or from our coal and iron mines, for a single day. The occurrence of diamonds in the United States, Mr. Kunz tells us, is chiefly confined to two belts of country: one along the eastern base of the Alleghanies, from Virginia to Georgia; the other along the western base of the Sierra Nevada and Cascade Ranges in Oregon and northern California. The Dewey diamond, found at Manchester, Va., in 1855, weighed before cutting 233/4 carats, and 1111/16 carats afterward. It passed through several hands, becoming the property of John A. Morrissey, who had made a loan of six thousand dollars on it. As it is off-color and imperfect, it is to-day worth not more than three or four hundred dollars. Mr. Kunz gives the history of the finding of a number of other American diamonds, many of which were picked up by children, or by persons knowing nothing of mineralogy. Some of these were destroyed by being struck with a hammer, their finders having an idea that this was a test which a diamond ought to stand. He also tells of reported finds of diamonds in which the stone turned out to be a quartz crystal which had been rolled among the gravel of some stream till it had acquired the appearance of a rough diamond.

Pieces of blue glass similarly worn into the shape of pebbles have been taken for sapphires. The largest crystal of sapphire ever found is in the Shepard mineral collection at Amherst College. It weighs three hundred and twelve pounds, is a perfectly terminated prism, partly red and partly blue in color, but opaque. It was obtained by Mr. C. W. Jenks from his mine at Franklin, N. C. In his chapter on the turquoise Mr. Kunz tells of its use by the ancient Mexicans, and by the Indians of the Southwestern United States, and gives pictures of several ornaments of their workmanship. He tells where the ruby, topaz, and emerald are found, and where occur a large number of less valuable stones, such as the garnet, tourmaline, beryl, amethyst, opal, agate, jasper, silicified wood, lapis lazuli, moonstone, sunstone, obsidian, amber, jet, cat's-eye, serpentine, malachite, and very many more whose names are less familiar. His account of Chalcedony Park in Arizona, where there are great blocks and whole tree trunks turned to agate, is a very interesting portion of the book. There is also a remarkably attractive and fully illustrated chapter on pearls. The chief pearl-fishing grounds