Manual of Mineralogy: Including Observations on Mines, Rocks, Reduction of Ores, and the Applications of the Science to the Arts, with 260 Illustrations. Designed for the Use of Schools and Colleges

H. C. Peck, 1866 - 454 Seiten

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Seite 355 - To be a good material for roofing, it should split easily into even slates, and admit of being pierced for nails without fracturing, Moreover, it should not be absorbent of water, either by the surface or edges, which may be tested by weighing, after immersion for a while in water. It should also be free from pyrites, and every thing that can undergo decomposition on exposure.''* FLAGSTONES.
Seite 143 - Steatite is also used in the manufacture of porcelain , it makes the biscuit semi-transparent, but brittle and apt to break with slight changes of heat.
Seite 293 - The amount of arsenic varies from 0 to 10 per cent. One variety from Spain included 10 per cent, of platinum, and another from Hohenstein some gold ; another from Tuscany 2*7 per cent, of mercury. These varieties give off, before the blowpipe, fumes of arsenic and antimony, and after roasting yield a globule of copper.
Seite 79 - The rocks in which the diamond occurs in Brazil are either a ferruginous quartzose conglomerate, or a laminated granular quartz called Itacolumite. The latter rock occurs in the Urals, and diamonds have been found in it ; and it is also abundant in Georgia and North Carolina. In India the rock is a quartzose conglomerate.
Seite 82 - Fine drills are made of small splinters of bort, which are used for drilling other gems, and also for piercing holes in artificial teeth and vitreous substances generally. The diamond is also used for lenses for microscopes. When ground plano-convex, they have but slight chromatic aberration, and consequently a larger field, and but little los* of light, compared with similar lenses of other materials.
Seite 83 - ... generally divides it into two varieties : — First, Coal without Bitumen. Second, Coal with Bitumen. The first variety is known by the general name of Anthracite. It has however various local names. [ANTHRACITE.] It is sometimes very hard, and has a high lustre, and is often iridescent. Besides being used for fuel it is often made into inkstands, small boxes, and other articles of use. This is more especially the case with the Anthracite of America. It is the most common form of coal in the...
Seite 349 - W,hen i> contains hornblende in place of mica, it is called syenite , hornblende resembles mica in these rocks but the laminae separate much less easily and are brittle. Granite is said to be micaceous, feldspathic, or quartzose, according as the mica, feldspar, or quartz, predominates. It is called porphyritic granite, when the feldspar is in large crystals, and appears over a worn surface like thickly scattered white blotches, often rectangular in shape. Graphic granite has an appearance of small...
Seite 258 - ... is formed in low places from the decomposition of minerals containing manganese. Gives off much water when heated, and affords a violet glass with borax. Obs. Wad is abundant in Columbia and Dutchess counties, NY, at Austerlitz, Canaan...
Seite 290 - The vitreous copper ore resembles vitreous silver ore ; but the luster of a surface of fracture is less brilliant, and they afford different results before the blowpipe. The solution made by putting a piece of the ore in nitric acid, covers an iron plate (or knife blade) with copper, while a similar solution of the silver ore covers a copper plate with silver.
Seite 359 - such was the care of the ancients to provide strong and durable materials for their public edifices, that but for the desolating hands of modern barbarians, in peace and in war, most of the temples and other public monuments of Greece and Rome would have remained perfect at the present day, uninjured by the elements during 2000 years. The contrast in this respect of the works of modern architects, especially in Great Britain...

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