Obrazy na stronie

Richter obtained this metal in the following man. ner: he exposed the oxyd of nickel to a sufficiently strong heat, and obtained one ounce of nickel; the rest was converted to a kind of scoriæ. This matter was reduced to powder, mixed with charcoal, and exposed for 18 hours to the strongest heat of a porcelain furnace. Under a blackish brown scoriæ, he obtained a metallic button, which weighed 2 ounces, to which he gave the name of nicolanum. The general pro. perties of this metal are : Its colour is steel gray with a shade of red. It is slightly malleable while cold. It is attracted by the magnet. Its specific gravity after fusion is 8.55 ; when hammered 8.60. It is soluble in nitric acid, the solution has a blackish green colour, which galatinizes when concentrated. When the solution is evaporated, a black powder, or oxyd of nicolanum, remains. This oxyd is insoluble in nitric acid, unless some sugar or alcohol be added to the mixture. It dissolves in muriatic acid, while oxymuriatic acid exhales. The solution is green. The sulphate of nicolanum exhibits the same phenomena. Carbonate of potash precipitates nicolanum from its solution of a pale blue colour. Ammonia renders the solution red, but occasions no precipitate. There are two oxyds of nicolanum ; the first is greenish blue, the second black.

For further particulars, see Gehlen's Journal, iv. 392. and v. 394.



Experiment 1. If tin ore be pulverised, mixed with charcoal, and exposed to a sufficient heat, the metal will be obtained; or,

Experiment 2. If the ore be roasted, and afterwards mixed with equal parts of potash, one half of commor

rosin, and two parts of black Aux, and the mixture fused in a crucible covered with charcoal, a button of metallic tin will be formed.

Rationale. The roasting dissipates the sulphur, and the subsequent process disengages the oxygen, if it be present, leaving the metal in the crucible. Pure tin may be obtained in the following manner :

Experiment 3. Let the tin obtained before be rapidly dissolved in strong nitric acid with heat. Thus some of the metals it may contain will be held in solution, and others become oxydated; but muriatic, or nitromuriatic acid will, on digestion, take up these oxyds, and after sufficient ablution leave that of tin, which may afterwards be reduced by mixing it when pulverised with double its weight of a flux formed of equal parts of pitch and borax, or resin and borax, and putting it into a covered crucible, lined with charcoal, which must be placed in a forge, and strongly heated for a quarter of an hour.

The analysis of ores of tin may be accomplished in the following manner, for which we are indebted to Klaproth :

Experiment 4. Boil 100 grains, in a silver vessel, with a solution of 600 grains of pure potash. Evaporate to dryness, and then ignite, moderately, for half an hour. Add boiling water, and, if any remain undissolved, let it undergo a similar treatment.

Saturate the alkaline solution with muriatic acid, which will throw down an oxyd of tin. Let this be re-dissolved by an excess of muriatic acid ; again precipitated by carbonate of soda; and being dried and weighed, let it, after lixiviation, be once more dissolved in muriatic acid. The insoluble part consists of silex. Into the colourless solution, diluted with two or three parts of water, put a stick of zinc, round which the reduced tin will collect. Scrape off the deposit,wash, dry, and fuse it under a cover of tallow in a capsule placed on charcoal. A button of pure metallic tin will remain at the bottom, the weight of which, deducted from that of the ore, indicates the proportion of oxygen.

The presence of tin in an ore is indicated by a pur

ple precipitate, on mixing its solution in muriatic acid with one of gold in nitro-muriatic acid.

Remark. The ores of tin, which are either oxyds or sulphurets, are enumerated in the general classification of ores. Tin, in its native state, is said to have been discovered in Cornwall, but its existence is rather questionable.

M. Klaproth analysed six varieties of the native oxyd of tin, from which the following comparative view of the proportion of metallic tin contained in them, is deduced.


Grs. 100 of stream tin, from Alternon in Cornwall, sp. gr. 6.97, gave of metallic tin

76 100 of brown crystallized tin stone from Schlackenwalde in Bohemia, sp. gr. 6.76, gave

72.5 100 of wood-tin from Cornwall, sp. gr. 6.45, gave

73 100 of crystallized gray tin stone, having some

white transparent spots, from St. Agnes in
Cornwall, sp. gr. 6.84, gave

74 100 of black stream tin from Ladock in Cornwall, sp. gr. 6.96, gave

76 100 of light brown acicularly crystallized tin stone

from Polgooth in Cornwall, sp. gr. 6.75,


Tin has been known from the earliest ages. It was in common use in the time of Moses.* It is mentioned by Homer. It was brought from Cornwall to England, by the Phænicians and Greeks, some centuries before the Christian era.f It is mentioned by Aristotle under the Greek name of Celtic tin.

* Numbers, xxxi. 22.

† Pliny states (lib. iv. cap. 54. and lib. xxxiv. cap. 47.) that the Phænicians procured it from Spain as well as from England.

This metal is of a white colour. Its hardness is 6. Its specific gravity is 7.291. It is very malleable. Tin leaf, or tin foil, is about Todo part of an inch thick. A tin wire t's.r inch in diameter is capable of supporting a weight of 31 pounds without breaking. At the temperature of 442° it melts. At a violent heat it evaporates. When cooled slowly, it may be obtained crystallized in the form of a rhomboidal prism.

It loses its lustre when exposed to the air, and assumes a greyish white colour, but when the vapour of water is made to pass over it in the state of ignition, the water is decomposed, the tin is oxydized, and hydrogen gas is disengaged. When tin is melted in an open vessel, its surface becomes very soon covered with a grey powder, or oxyd of the metal. When heated violently it takes fire, and is converted into a fine white oxyd. Tin is capable of combining with three different proportions of oxygen, and of forming three distinct oxyds. Two of them have been named the yellow and the white oxyd. The gray oxyd may be obtained in the following manner :

Experiment 5. Dissolve tin in muriatic acid, either by means of heat, or by adding a little nitric acid occasionally. When the solution is formed decompose it by adding an excess of potash ; a white powder will precipitate, which, in part will be taken up. But the remainder on standing, will assume a dark grey colour, which is the grey oxyd of tin. According to Proust, this oxyd contains 20 per cent. of oxygen.

Experiment 6. If tin be dissolved in concentrated nitric acid, a violent action will take place, and the metal be converted into a white powder, which is deposited at the bottom of the vessel.

Rationale. The nitric acid is decomposed ; nitric oxyd gas is disengaged ; and the tin is oxydized to the maximum, forming the per oxyd. This oxyd is composed of about 28 parts of oxygen and 72 of tin.

Experiment 7. If granulated tin be dissolved in dilute nitric acid, and the solution decomposed by the addition of potash, a yellow oxyd of tin will be precipitated.


Rationale. The nitric acid unites with the metal, forming a nitrate which is decomposed by the potash; nitrate of potash is produced and the metal is precipitated in the form of a yellow oxyd.

Experiment 8. If five parts of concentrated sulphuric acid, and one part of granulated tin, be introduced into a flask and digested, a solution of the metal will take place.

Rationale. The metal is oxydized at the expense of the acid ; sulphurous acid gas is disengaged, and the metal is dissolved.

Experiment 9. If the solution of tin, of the last experiment, be evaporated, crystals of sulphate of tin will be produced.

Experiment 10. If one part of uin, be added to two parts of muriatic acid, it will be dissolved, forming muriate of tin.

Rationale. The metal is oxydized by the water contained in the acid; hydrogen gas is evolved ; and the oxyd of tin, thus produced, is then dissoived.

Experiment 11. If the solution of the last experiment be evaporated, crystals of muriate of tin will be forined.

Experiment 12. If two parts of nitro-muriatic acid be introduced into a flask, and one part of tin gradually added, a solution of the metal will take place.

Experiment 13. If equal parts of grained tin and muriate of ammonia be mixed, and introduced into a retort, and heat applied; ammonia will come over, leaving a residuum of solid muriate of tin.

Rationale. The muriate of ammonia is decomposed; the tin is oxydized, and the oxyd combines with the muriatic acid, forming muriate of tin, whilst the ammonia is disengaged in the form of gas.

Experiment 14. If five parts of tin and one of mercury be fused together, the mixture then triturated with an equal quantity of corrosive muriate of mercury, and the whole introduced into a retort and distilled, the oxymuriate of tin, or the smoking liyuor of Libavius will be obtained.

[ocr errors][ocr errors]
« PoprzedniaDalej »