United States or Norfolk Island ? Vote for the TOP Country of the Week !
The rocks are of many kinds, white laminated, sometimes siliceous sandstone, purple and red sandstone, sometimes so highly calcareous as to have a crystalline fracture, argillaceous limestone, black calcareous slate-rock, like that so often described at Copiapo and other places, thinly laminated, fine-grained, greenish, indurated, sedimentary, fusible rocks, approaching in character to the so- called pseudo-honestone of Chile, including thin contemporaneous veins of gypsum, and lastly, much calcareous, laminated porcelain jasper, of a green colour, with red spots, and of extremely easy fusibility: I noticed one conformable stratum of a freckled-brown, feldspathic lava.
Others finding fusibility joined with that yellow colour in certain parcels of matter, make of that combination a complex idea to which they give the name gold, to denote a sort of substances; and so exclude from being gold all such yellow shining bodies as by fire will be reduced to ashes; and admit to be of that species, or to be comprehended under that name gold, only such substances as having that shining yellow colour, will by fire be reduced to fusion, and not to ashes.
"Apprehending that the cause of it was, that the fusibility of the metal was impaired, by the violence of the fire," he says, "I ordered all my dishes and porringers, which were in number about two hundred, to be placed one by one before my tubes, and part of them to be thrown into the furnace, upon which all present perceived that my bronze was completely dissolved, and that my mould was filling," and, such was the relief that even the loss of the entire pewter service of the family was sustained with equanimity; the family, "without delay, procured earthen vessels to supply the place of the pewter dishes and porringers, and we all dined together very cheerfully."
No one of them indicates what the object is by itself, when left alone. They depend on contingent circumstances, and apart from these they would not exist what is color in the dark? what sound in airless space? what weight in empty space? what fusibility without fire? they are each and all relative.
Thus our idea of gold may at first be a yellow colour, weight, malleableness, fusibility; but upon the discovery of its dissolubility in aqua regia, we join that to the other qualities, and suppose it to belong to the substance as much as if its idea had from the beginning made a part of the compound one.
For, it is the real constitution of its insensible parts, on which depend all those properties of colour, weight, fusibility, fixedness, &c., which are to be found in it; which constitution we know not, and so, having no particular idea of, having no name that is the sign of it.
For, he that to the yellow shining colour of gold, got by sight, shall, from my enumerating them, have the ideas of great ductility, fusibility, fixedness, and solubility, in aqua regia, will have a perfecter idea of gold than he can have by seeing a piece of gold, and thereby imprinting in his mind only its obvious qualities.
Those geologists who have doubted whether granite could have been formed by igneous liquefaction, because minerals of different degrees of fusibility impress each other with their forms, could not have been aware of the fact of crystallised hornblende penetrating phonolite, a rock undoubtedly of igneous origin.
Apopholite is distinguished from calcite, as noticed under that species, and from the others by its form, difficult fusibility, and part solubility. Phrenite is characterized by its hardness, greenish color, occurrence, and action of acid. Iron pyrites is always known by its brassy metallic aspect and great hardness.
Nevertheless, the Indians must have known that fire melted copper; for the heat of the altars was great enough, say Squier and Davis, to fuse the implements and ornaments laid upon them in sacrificial rites; and so the fact of its fusibility could hardly have escaped them.
Word Of The Day