MINERALOGY.
571
te r — — _ — , , ...- - ■■ -- - - . ■ -
® u i|)hate of iron into the solution, and the geld is precipitated in, e metallic state. The copper, if any be present, may be preci-h'tated by a plate of iron. The presence of iron may be ascer-ja'Ued, by dropping tincture of nut-galls into a portion ofthesolu-ll on. The analysis of the ores of silver has been always considered" s Very important, on account of the great value of the metal.
. “ Native Silver is to be dissolved in nitric acid. The gold," the ore contains any, remains in the state of a black powder, and"'ay be dried and weighed. The silver may be precipitated byc °mmon salt: 100 parts of the precipitate, dried, denote about 75harts ofsilver. The presence of copper may be ascertained by the_S l 'een colour of the solution, and by the blue colour it assumes onRiding ammonia. The copper may be precipitated by a plate ofor by the rules laid down hereafter. When the ore contains"tsenic, its proportion may be estimated by weighing before and"her fusion ; for the arsenic is dissipated by heat, or the ore may" e dissolved in nitric acid, which acidities the arsenic. After theSe paration of the silver, the arsenic acid may be precipitated by""fate of lead ; 100 parts of the dry precipitate indicating about 22of the arsenic.
Alloy of Silver and Antimony is to be treated with"i'ric acid, which dissolves the silver, and oxidates the antimony._ he silver is estimated as above. The oxide of antimony may bej e duced by fusion with four times its weight of black llux and a lit-soap.
“ Sulphuret or Silver is to be treated with diluted nitric""hi, witch dissolves the silver, leaving the greater part of the sul-P Hir untouched. The residuum is to be dried, and then the sul-phur burnt off. The loss of weight gives the sulphur. The resi-pJUm i; the gangue of the ore, which may be analysed by the rules'"id down in the” last “ chapter. The silver is to be precipitatedb y common salt; and the other metals, if any be present, maybe" Pertained as above, l’art of the sulphur is always acidified. The" C| d tints formed may be precipitated by nitrate of barytes; 100parts of the dried precipitate indicating about 14.5 of sulphur.
“ Muriate of Silver was analysed by Klaproth as follows:parts were mixed with thrice their weight of pure carbonate ofPotass , and melted together in a glass-retort. The mass was dis-s °h'ed in water, and the solution filtered. A residuum remained,'J’h.ch was dissolved in nitric, acid, with the exception of a red pow-Utr ; which, treated with nitro-muriatic acid, was dissolved, ex-Ct! Pt a little muriate of silver, which, when reduced, yielded 0.5 ofPure silver. Ammonia precipitated from the nitro-muriatic soiu-, l0 U 2 - 5 parts oxide of iron. The nitric solution was precipitated"y common salt; the muriate of silver, thus obtained, yielded,,'?u«n reduced, 67-25 of pure silver. The original aqueous solu-■! 0l > of the alkaline mass was saturated with acetous acid, on whichf deposited 1-75 parts of alumina. The solution was evaporated"dryness, and the dry mass treated with alcohol, which dissolved" e acetite of potass. The residuum, amounting to 58'75 parts,dissolved in water; and being treated with muriate of barytes,"'teen parts of sulphate of barytes precipitated, indicating the pre-> S p," ce of about 0'5 of sulphuric acid, and 0'75 sulphate of potass.|he remaining 5S parts were muriate of potass, indicating about® harts muriatic acid.
» “ Native Coffer sometimes contains gold, silver, or iron.
' Nay be dissolved in nitric acid ; the gold remains in the state of^"lackish, or rather violet-coloured, powder; the silver may be“"Parated by a polished plate of copper; (or precipitated from aeNtion of the solution by common salt;) the iron may be sepa-a ^ed by boiling the solution to dryness, and treating the residuum''hi water. By this process, the nitrate of iron is decomposed ; theXl *le of iron remains, while the water dissolves the nitrate of cop-
per. This suit may be decomposed by boiling it with potass: theprecipitate dried in a red heat, is black oxide ot copper: 100 partsof it denote 80 of metallic copper.
“Sulphate of Coffer maybe dissolved in diluted nitricacid. Part of the sulphur remains unaltered, and may be estimatedby weighing it, and burning it off. Part is acidified, and may beprecipitated by nitrate ot barytes; 100 parts of the dried precipitateindicating 14‘5 of sulphur. By evaporation to dryness, and solu-tion in water, the iron is separated ; and the copper may be esti-mated as above; or muriatic acid maybe used instead of nitric :but in that case it is much more difficult to obtain a completesolution.
Arseniate of.Copper was thus analysed by Mr. Chevenix.The ore was dissolved in diluted nitric acid, nitrate of iead pouredin. The solution was evaporated till a precipitate began to appear,and then mixed with alcohol- Arseniate of lead precipitated : 100parts of this salt indicate 33 of arsenic acid. The copper wasseparated from the nitric acid by boiling it with potass.
“ Pyrites, or Sulphureted Iron, may be treated re-peatedly with boiling nitric acid, till the sulphur is acidified. M t.-riaticacid is then to be added, and the digestion continued till ti.ewhole be dissolved. Muriate of barytes is then to be added, toprecipitate the sulphuric acid ; 100 of the dried precipitate indi-cates 14‘5 of sulphur. If the solution contains only iron, it may-be precipitated by carbonate of soda, calcined to redn<\.s andweighed. But if earths or manganese be present, we must proceedby the rules laid down above for those substances.
The Sulphuret of Tin was thus analysed by Klaproth :120 parts of the ore was digested with nitro-muriatic acid; 43 partsremained undissolved. Of these, 30 burnt away with a blue liame,and were sulphur; of the remaining 13, eight dissolved in nitro-muriatic acid. The undissolved five were heated with wax, andyielded a grain of iron attracted by tire magnet. The re.-t wasa mixture ot alumina and silica. The nitro-muriatic solution wascompletely precipitated by potass, and the precipitate redissolvedin muriatic acid. A cylinder of tin precipitated 44 parts of copperfrom this solution, and lost itself 89 parts of its weight. A cylin-der of zinc precipitated 130 parts of tin ; so that deducting the 89parts of tin dissolved during the precipitation of the copper, 41 re-mained for the tin contained in the ore.
“ Sulphuret of Lead usually contains a little silver, andsometimes also antimony and zinc. It may be treated with dilutednitric acid, which leaves only the sulphur undissolved, the weightof which is to betaken, and its purity determined by combustion.If antimony be present, it will either remain in the state of a whiteoxide, or, if dissolved, will be precipitated by diluting the solutionwith water. Muriatic acid is to be added, and the solution evapo-rated till it is reduced to a small portion. Muriate of lead and ofsilver precipitate. The first of these may be dissolved in boilingwater; the second remains insoluble. YVestrum separated themuriate ofsilver, by digesting the precipitate with ammonia. Theliquid, from which the muriates are separated may contain iron,zinc, and copper. The iron may be precipitated by ammonia addedin excess ; the copper by a plate of zinc: the zinc by carbonate otsoda, reduced to the metallic state and weighed, subtracting whathad been separated from the plate of zinc.
“ Carbonate of Lead may be dissolved in nitric acid, col-lecting and estimating the carbonic acid. By boiling the solution,the iron and antimony (if present) will be separated, and may beestimated by solution in muriatic acid; precipitating the antimonyby water, and the iron by ammonia. From the nitric solution theiead may be precipitated by sulphuric, acid, and the earth may beexamined by the rules laid down above.’
^INF.BVA, ATHENA, or PALLAS, in Pagan worship, thej?°ddess of sciences and of wisdom, who sprung completely armeda t°I" Jupiter’s brain ; and on the day of her nativity it rained goldBhodes. She disputed with Neptune the lionour ot giving a,Tle t 0 tb e capital of Cecropia , • when they agreed that vvhoso-t j. °f them should produce what was most useful to mankind,"Id have that advantage, Neptune, with a stroke of his trident,
formed a horse; and Minerva caused an olive to spring from theground, which was judged by the unanimous voice of the gods to.be the most useful, from its being the symbol of peace ; whereuponshe gave her name Athena: to the city, and became its tutelar god -dess, Minerva is usually represented by the poets, painters, andsculptors, completely armed, with a composed but agreeable! countenance, bearing a golden breast-plate, a spear in her right-
9 hand.