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Remark. Adet has published a very interesting memoir on this production. From the observations of this chemist it appears, 1st, that the oxygenated muriate of tin is a saline substance, formed by the combination of tin with oxygenated muriatic acid deprived of water. 2d. That if it be mixed with water in the proportion of seven to twenty-two, a concrete saline substance will be obtained. 3d. That when diluted with water, it can dissolve a new quantity of tin without a disengagement of hydrogen gas. According to these facts, it is a true oxygenated muriate of tin.

Experiment 15. Having found a piece of blue linen cloth, that will bleach in oxygenized muriatic acid, dip the tip of the finger in a solution of muriate of tin, and press it while wet with the solution, upon a strip of this cloth. After an interval of a few minutes immerse the cloth in the vial of liquid oxygenized muriatic acid, and when it has remained in it the usual time, it will be found that the spot which was previously wet with muriate of tin has preserved its original colour, while the rest of the cloth has become white.

Experiment 16. Dip a piece of white calico in a strong solution of acetate of iron; dry it by the fire, and lay it aside for three or four days. After this, wash it well in hot water, and then dye it black, by boiling it for ten minutes in a strong decoction of Brazil wood. If the cloth be now dried, any figures printed upon it with a colourless solution of muriate of tin will appear of a beautiful scarlet, although the ground will remain a permanent black."

Experiment 17. Take a piece of very dark olive coloured linen that has been dyed with iron and quercitron bark, or weld, and spot it in several places with a colourless solution of muriate of tin. Wherever the cloth has been touched with this solution, the original colour will be discharged, and spots of a bright yellow will appear in its stead.

Experiment 18. Boil a little cochineal in water with a grain or two of cream of tartar (supertartrate of potass) and a dull kind of crimson solution will be formed. By the addition of a few drops of nitro-muriate of

tin, the colouring matter will be precipitated of a beautiful scarlet. This, and some of the former instances,

See

will give the student a tolerably correct idea of the general processes of dyeing woollen cloths. light.*

The union of white oxyd of tin with sulphur by fusion, forms yellow sulphuretted oxyd of tin (aurum musivum.)

Experiment 19. The process generally adhered to in this preparation is as follows: twelve parts of tin are melted in a crucible by a brisk fire, and three of mercury added to it. This mass is to be reduced to powder in a stone mortar, and then intimately mixed by trituration with seven parts of sulphur, and three of muriate of ammonia: the mixture is exposed to heat as long as any white vapours are disengaged; the heat is then moderately increased; a little sulphuret of mercury and some oxygenated muriate of tin sublime, and the aurum musivum remains at the bottom of the mattrass.

A variation in the proportion of the ingredients produces no very essential change in the result. Pelletier obtained a very beautiful musive gold by distilling together equal parts of mercury, muriate of ammonia, tin, and sulphur. The main point is the proper regulation of the heat; if this be too strong the operation does not succeed, and instead of a beautiful au um musivum, common sulphuret of tin, of a very dark colour, is obtained.

Rationale. The theory of the formation of this compound is one of the most intricate in chemistry, but it appears to have been sufficiently ascertained by the researches of Pelletier. In the first amalgamation and trituration of the mercury and tin, the latter is divided,

* Parke.

and in some degree oxydated; when the mixture of this amalgam with the sulphur and muriate of ammonia is heated, the muriatic acid, by a disposing affinity, enables the tin to be oxydated by decomposing the water, and this oxyd combines with the muriatic acid; the hydrogen of the water is disengaged with the ammonia of the muriate of ammonia; this ammonia unites with a portion of the sulphur, and forms sulphuret of ammonia, which being disengaged, causes the white fumes. The heat being now augmented, the muriate of tin is again decomposed, the oxyd of the metal attracting a portion of the sulphur, and forming the aurum musivum. Such is the aetiology of that complicated process given by Pelletier.

Aurum musivum is employed to give a beautiful colour to bronze, and to excite the strength of electrical machines. It is used by japanners, and for many articles intended to have the appearance of metallic gold.*

Tin combines very readily with sulphur ; as,

Experiment 20. By fusing together, in a covered crucible, one part of tin with four or five of sulphur. The compound is heavier than tin, and not so fusi

ble.

Tin combines also with phosphorus; as follows:

Experiment 21. Take equal parts of tin filings and. glacial acid of phosphorus, and one eighth part of charcoal powder: mix these three substances intimately, and fuse them in a crucible; a few grains of a metallic appearance, and of a pretty large size, will be obtained. These do not differ in appearance from tin, but when melted by the blow-pipe, the phosphorous abandons the metal and burns on its surface.

Remark. In fusing tin with charcoal powder and glacial acid of phosphorus, care must be taken to regu

* Accum.

late the fire properly, for the phosphorous easily abandons the metal.

The accension of tin-foil by nitrate of copper, mentioned under affinity, the decomposition of nitrate and oxymuriate of potash by tin, causing detonation, shews that this metal, like the others, is inflammable and capable of combining with oxygen.

With the metals, tin is capable of combining, and forming alloys of a peculiar nature. Thus we have alloys of tin with gold, platinum, silver, mercury, copper, iron, &c.

Tinning copper vessels.

Vessels of copper, especially when used as kitchen utensils, are usually covered with a thin coat of tin, to prevent the copper from oxydating, and to preserve the food which is prepared in them from being mixed with any of that poisonous metal. These vessels are then said to be tinned. Their interior surface is scraped very clean with an iron instrument, and rubbed over with muriate of ammonia. The vessel is then heated, and a little pitch thrown into it, and allowed to spread on the surface. Then a bit of tin is applied all over the hot copper, which instantly assumes a silvery whiteness. The intention of the previous steps of the process is to have the surface of the copper perfectly pure and metallic; for tin will not combine with the oxyd of copper. The coat of tin thus applied is exceedingly thin. Bayen ascertained, that a pan nine inches in diameter, and three inches three lines in depth, when tinned, only acquired an additional weight of 21 grains. Nor is there any method of making the coat thicker. More tin indeed may be applied; but a moderate heat melts it, and causes it to run off.

The alloy or amalgam of mercury and tin is used in silvering the backs of looking glasses A sheet of tin foil is spread upon a table, and mercury rubbed upon it by a hare's foot, till the two metals incorporate;

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then a plate of glass is slid over it, and kept down with weights. The excess of mercury is driven off, and in a short time the tin foil adheres to the glass and converts it into a mirror. Two ounces of mercury are requisite for covering three square feet of glass.

Iron is tinned in the following manner: plates of iron, after being reduced to a proper thickness, are immersed in water acidulated with sulphuric or muriatic acid, in order to clean them completely from rust; they are then scoured quite bright, and placed in a pot, or other convenient vessel, filled with melted tin, whose surface is covered with suet, pitch, or rosin, to prevent the surface of the tin being oxydated. The plates of iron being then suffered to pass through it, the tin will unite with them so as to cover each side of the plate with a thin white coat. They are then what are called tin plates.

In the same way stirrups, buckles, bridle bits, &c. are covered with coats of tin.

Tin plate is known in Scotland by the name of white iron.

The alloys of copper and tin have already been noticed. See Copper.

Besides the union of copper and tin, for the formation of gun metal, bell metal, bronze, &c. it is asserted that the conch of the East Indians is composed of the same metals.

Three parts of tin, five of bismuth, and two of lead, forms the alloy, or soft solder of Lichtenburg. According to Wallerius, two parts of tin with one of bismuth forms the Tutenag of the Chinese. Equal parts of tin and zinc, with two parts of mercury, melted together, forms the amalgam for exciting electrical machines. Tin enters into the composition of pewter, enamel, &c.

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