A manual of mineralogy: in which is shown how much Cornwall contributes to the illustration of the science ...

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W. Polyblank, 1825 - 245 pages
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Page 45 - ... bring it to the proper pitch. The copper in this state is what is termed dry. It is brittle, is of a deep red colour, inclining to purple, an open grain, and a crystalline structure. In the process of toughening, the surface of the metal in the furnace, is first well covered with charcoal. A pole, commonly of birch, is then held in the liquid metal, which causes considerable ebullition, owing to the evolution of gaseous matter; and this operation of poling is continued, adding occasionally fresh...
Page 44 - ... last operations in the works which contain some oxide of copper, as likewise pieces of furnace bottoms impregnated with metal : the chemical effect which takes place is, that the oxide of copper in the slags becomes reduced by a portion of the sulphur, which combines with the oxygen, and passes off as sulphurous acid gas, while the metal thus reduced enters into combination with the sulphuret.
Page 223 - Axis of a crystal — The lateral planes surround its axis, which is an imaginary line passing down the middle of the prism from the centre of the upper to that of the lower terminal plane.
Page 220 - The alkali decomposed with bright scintillations, and the reduced metal being separated, afterward burnt. The small particles which remained a few moments before they were reconverted into alkali, and allowed a short examination, were of a white colour, and very similar to sodium. A globule of quicksilver made negative, and brought into contact with the alkaline salt, soon became an amalgam of lithium, and had gained the power of acting on water, and evolving hydrogen, an alkaline solution resulting.
Page 223 - ... Tubes or pipes of iron or wood, for ventilating underground, or for the conveyance of fresh air into levels having but one communication with the atmosphere, and consequently no current of air. Aitch-piece — That part of a plunger-lift in which the clacks are fixed. Alliaceous — The garlic odor of arsenical minerals when heated or struck. Amorphous — Without form. Anhydrous — Without water of crystallization. Arborescent — Ramifying like a tree. Arch — A piece of ground left unworked...
Page 46 - ... supported over a cistern of water. The water may be either hot or cold, according to the form to be given to the metal. When warm, the copper assumes a round form, and is called bean shot. When a constant supply of cold water is kept up, the metal has a light ragged appearance, and is called feathered shot. The former is the state in which it is prepared for brass wire-making. Another form into which copper is cast, chiefly for exports to the East Indies, is in pieces of the length .of six inches,...
Page 75 - ... chisel and hammer a piece of one of the lower corners of the block, about a pound weight, partly by cutting and partly by breaking, in order to prove the roughness [query toughness ?] and firmness of the metal. If it is a pure good tin, the face of the block is stamped with the duchy seal, which stamp is a permit for the owner to sell, and, at the same time, an assurance that the tin so marked has been examined and found merchantable. The stamping of this impression by a hammer is coining the...
Page 85 - ... parts by filing or hammering : but it may be granulated, like the malleable metals, by pouring it, when fused, into cold water ; or, if it be heated nearly to melting, it is then sufficiently brittle to be pulverized. It melts at about 700 Fahrenheit, and soon afterwards becomes red hot, burning with a dazzling white flame of a bluish or yellowish tinge, and is oxidized with such rapidity that it flies up in the form of white flowers, which are calledyfotw* of zinc, or philosophical wool.
Page 68 - The alloys of steel with platinum, when both are in a state of fusion, are very perfect, in every proportion that has been tried. Equal parts by weight form a beautiful alloy, which takes a fine polish, and does not tarnish ; the colour is the finest imaginable for a mirror.
Page xvii - And if the weight of the body in the air be divided by what it loses in water, the quotient will shew how much that body is heavier than its bulk of water. Thus, if a guinea, suspended in air, be counterbalanced by 129 grains in the opposite scale of the balance ; and then...

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