Manual of Mineralogy

Durrie & Peck, 1855 - 432 Seiten

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Seite 49 - ... be produced in the same direction ; then the sum of the exterior angles A, B, C, D, E, will be equal to four right angles. For each interior angle, together with its adjacent exterior angle, is equal to two right angles (Prop.
Seite 236 - ... cementation ? Because it consists in heating bars of the purest iron in contact with charcoal ; it absorbs carbon, and increases in weight, at the same time acquiring a blistered surface. This, when drawn down into smaller bars, and beaten, forms tilted steel ; and this broken up, heated, welded, and again drawn out into bars, forms shear-steel. In this process it has been commonly considered that the carbon combines mechanically with the iron ; our chemists have, however, long been of opinion,...
Seite 315 - ... reduced to a manageable quantity, the gold is amalgamated with clean mercury ; the amalgam is next strained to separate any excess of mercury, and finally is heated and the mercury expelled, leaving the gold.
Seite 343 - 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 two thousand years.
Seite 308 - Extraction of Palladium in Brazil. The extraction of palladium, from the auriferous sand of Brazil, consists in fusing it with silver, and, consequently, forming a quaternary alloy of gold, palladium, silver, and copper, which is granulated by projecting it into water. By treating this alloy with nitric acid, the gold is separated from the other metals which are soluble in the acid; the silver is precipitated by a solution of common salt in the state of insoluble chloride, which being separated,...
Seite 81 - 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 401 - ... and of various degrees of glassy lustre to a dull stone without the slightest glistening. The common grayish cobble-stones of the fields are usually quartz, and others are dull red and brown ; from these there are gradual transitions to the pellucid quartz crystal that looks like the best of glass. Sandstones and freestones are often wholly quartz, and the seashore sands are mostly of the same material. It is therefore probable that this mineral will be often encountered in mineralogical rambles.
Seite 273 - Dissolves in heated nitric acid, with a precipitation of the sulphur. Dif. 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. Obs. Occurs with other copper ores in beds and veins. At Cornwall,...
Seite 283 - ... its weight of sawdust, then imbued with oil, and heated moderately in a crucible, till all the arsenical fumes be dissipated. The residuum, being cooled and triturated...
Seite 85 - ... 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...

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