SILVER, which is divided by mineralo gists into three species, the native, anti monis!, and the arsenical, has been rec koned among the noble or perfect me tals, and has been known from the earliest ages of the world. Its scarcity, beauty, and utility, have always rendered it an object of research among mankind, so that the nature and properties of this me tal have been long studied and minutely investigated. In the midst of the rage for the transmutation of metals, which for centuries fired the imaginations of the al chymists, silver occupied a great share of their attention and labour, with the hope of discovering the means of converting the baser and more abundant metals into this, which is more highly valued on ac count of its scarcity and durability. When the dawn of science commenced, and its light had dissipated the follies and extra vagances of these pursuits, the earliest chemists were much employed in examin ing the properties and combinations of silver; nor has it been overlooked or ne glected by the moderns. Silver, which is neither in such abundance nor so univer sally diffused as many other metals, exists in nature in five different states ; in the native state ; in that of alloy with other metals, especially with antimony; in that of sulphuret, sulphurated oxide, muriate, and carbonate.
1. Native silver, which is characterized by its ductility and specific gravity, is fre quently tarnished on the surface, ofa or blackish colour, and appears under a great variety of forms. In this state it is not perfectly pure. It is usually alloyed with a little gold or copper.
2. The alloy of silver and antimony, which is the most frequent, is distinguish. ad by its brittleness and lamellated struc ture from native silver, which it resembles in lustre and colour It crystallizes in prisms, which are six-sided, regular.
3. The sulphuret of silver, which is known to mineralogists by the name of vitreous silver ore, is of a dark grey co lour, and has some metallic lustre. dt is usu ally crystallized in the form of cubes, octahedrons with angular facets, or sometimes in the form of the dodeca hedron.
4. The sttlphurated oxide of silver and antimony. In this ore of silver the sul phur is combined with the metal in this state of oxide ; in the former, in the me tallic state. This ore is called red silver ore. It is of a deep red colour, some times transparent, and sometimes nearly opaque, frequently having the lustre of steel on the surface. The primitive form of its crystals is the rhomboidal dodeca hedron.
5. The muriate of silver, which has been long known to mineralogists by the name of corneous silver, is found in irre gular masses, of a greyish colour, fre quently opaque, hut sometimes semi transparent. It is soft, and very fusible.
Native silver is generally found in irre gular shapes ; sometimes in masses of no determined form, sometimes branched, occasionally in capillary filaments, and not uncommonly in leaves. Thus it ap pears in most mines, and particularly in those of Siberia, where Patrin tells us he never met with it crystallized. It is found in the mines of Peru in a vegetable form, imitatingthe leaves of fern. This variety of figure in native silver is occasioned by a vast number of little eight-sided crys tals, so disposed upon each other as to give the whole the appearance of a vege table. The curved cylindrical filaments, in which form silver is sometimes found, are of various sizes, from the thickness of a finger, to the diminutive size of a hair. Native silver, as we have observed, is seldom found pure, but is generally mixed with other metals ; such as gold, cooper, mercury, iron, lead, &c. This last metal almost always contains a por tion of silver, though frequently so small as not to be worth the expense of sepa rating it. In the reign of Edward the First nearly 1600 pounds weight of sil ver were obtained, in the course of three years, from a mine in Devonshire, which had been discovered about the year 900. The lead mines in Cardiganshire have, at different periods, afforded great quanti ties of silver. Sir Hugh Middleton is said to have cleared from them 2000 pounds in a month. The same mines yielded, about the year 1745, eighty ounces of silver out of every ton of lead. The lead ores from Brunghill and Ske korn produced also a considerable quan tity of 'liver. The lead only, in one of the smelting houses at Holywell, in Flint shire, produced no less than 31,521 ounces, or 3126•1 pounds of silver, from the year 1754 to 1776. "There are
some lead ores in this country." says Dr. Watson, " which, though very poor in lead, contain between three and four hun dred ounces of silver in a ton of that me tal. It is commonly observed. that the poorest lead-ores yield the most silver, so that a large quantity of silver is probably thrown away in England, from not hav ing the poorest sort of lead-ores properly assayed." Salver in its mineral state occurs mas sive, disseminated, in blunt cornered piece, in plates, and in membranes : it is said to occur also in Spanish America in rolled pieces. Its crystallizations are very various, as the cube, octahedron, prism, pyramidal, &c. : the crystals are small and microscopic. It is chiefly found in primi tive earths, especially in those which are depositied in beds, though it is not confin ed to these alone. It is very rarely met with in granite, but not uncommonly in the fissures of micaceous rocks, and in other places of a similar nature. but of more recent formation. In the secondary earths silver often occurs, being found in chalk, slate, &c.; but almost always mi neralized by sulphur or arsenic. It is a singular fact, that the situations of gold and silver mines should often be diame trically opposite in point of tempera. ture. Gold is common in the hottest parts of the earth, while we generally find silver mines in the cold regions. Thus, the chief parts of the world where silver is to be met with are, Sweden, Norway, and the higher latitudes near the pole : if we find it in hot climates, it is seldom on level ground ; but, on the cortrary, raised to a great height, to wards the tops of mountains that are per petually covered with ice and snow. It is thus situated in the Alpine mountains of Europe and America; and such are the mines of Allemont in France, and those of Potosi in the Andes. The prin cipal silver mine in Europe is that of Ko nigsberg, in Norway, to the north of Christiana. This is the richest, the most important, and one of the most sin gular mines in that quarter of the globe. The district in which it is situated is mountainous; and the mines are divided into superior and inferior, on account of their relative position. The earth is com posed of beds nearly in a vertical posi tion, and running from north to south. Some are composed of quartz mixed with mica, of granite and of chalk: while others are formed of whitish-grey quartz, mixed with fine blackish mica, or else consists of ferruginous rock. These beds are of very considerable thickness, and contain a great quantity of native as well as of mineralized silver. The veins are richer in mineral, and their produce more considerable, where they traverse the beds of ferruginous rock, than in any other part. The most remarkable mine of silver in Spain is that of Guadalcanal, in Andalusia, which was formerly very rich, and well known to the Romans. It is situated in the Sierra Morena, or black mountain, on the confines of Andalusia and Estremadura, fifteen leagues to the north of Seville, and several miles to the north-east of the famous quicksilver mine at Ald Almaden. The mineral obtained here is the ruby silver ore. But it is in the centre of the Andes, in situations which, though immediately exposed to the perpendicular rays of the sun, are constantly covered with snow, that na ture has most abundantly distributed this metal. In twenty degrees of southern la titude, within the torrid zone, we find the famous mountain of Potosi, situated near the source of the Rio de la Plata. This mountain is one of the most considerable in Peru ; its height is immense • and it appears, from the description of travel lers, that from top to bottom it is full of veins of silver. When these mines were first discovered, in the year 1545, the veins were so rich as to be almost entirely composed of silver without any mixture. At present, however, the produce is very different,scarcely more than five drachms being obtained from a hundred weight of ore ; still, from the great abundance of mineral, the produce is very consider able. According to the observations of several Spanish naturalists, the mountain of Potosi alone, from the time it was first discovered, in 1545, till the year 1638, that is, in the space of ninety-three years, yielded four hundred millions of pesos, or ounces of silver.