or TIN-GLASS, one of the semi-metals, of a reddish or yellowish-white colour and a lamellated texture, and moderately hard and brittle, so that it not only breaks into pieces under the strokes of the hammer, but may even be beat into powder. It is the heaviest of all the semimetals, weighing from 9,600 to 9,700, and is about as fusible as lead. It is found,
1. Native. Bismuth is found more commonly in a native state than any other metallic substance. It is usually crystallized in cubes or octagons, or in the form of dendrites or thin laminae investing the ores of other metals, particularly cobalt.
2. Native Cals of Bismuth, in which the metal is mineralized by aerial acid; is either in form of a powder or indurated like mortar. It is frequently of a greenish-yellow colour, being mixed with the ores of other metals. The red and yellow part is most commonly cobalt ore; though it has often been mistaken for bismuth. It is frequently found in glittering particles bismuth interspersed through stones of various kinds. Silver, iron, and other metals, are also found in it.
3. Mineralized by the Vitriolic Acid. This is said to be of a yellowish, reddish, or variegated colour, and to be found mixed with the calx of bismuth incrusting other ores.
4. By Sulphur. This is found chiefly in Sweden, is of a bluish-grey colour, a lamellated texture and tessellar form like galena, but much heavier; sometimes presenting parallel striæ like antimony. It is said to contain cobalt and arsenic as well as bismuth. It is very fusible, and the sulphur it contains may be mostly separated by scorification.
5. By Sulphur and Iron. This ore is said to be of a lamellar cuneiform texture, and to be found in Norway. This kind of ore yields a fine radiated regulus; for which reason it has been ranked among the antimonial ores by those who have not taken proper care to melt from it a pure regulus, or one deficient of sulphur. In Schneeberg they have what is called columbine bismuth and plumose bismuth; the former taking its name from the colour, the latter from its texture. The latter is said to contain a great quantity of cobalt.
6. With Sulphur and Arsenic. This ore is generally of a whitish-yellow or ash colour, has a shining appearance, and is composed of small scales or plates intermixed with small yellow flakes. Its texture is hard and solid; sometimes it strikes fire with steel. It has a disagreeable smell when rubbed; does not effervesc with acids, but is partially dissolved by the nitrous acid. The solution, diluted with water, becomes a kind of sympathetic ink; the words written with it on white paper being invisible when dry, but assuming a yellowish colour when heated before the fire. There is also a grey bismuth ore of the arsenicated kind, with a striated form, found at Helsingland in Sweden and at Annaberg in Germany. Another of the same kind, with variegated colours of red, blue, and yellowish-grey, is likewise found at Schneeberg in Saxony. At Misnia in Germany, and at Gillebeck in Norway, it is also found interlaid with green fibres like an amaranthus. At Georgenstadt in Germany, and at Annaberg in Saxony, it is intermixed with reddish-yellow shining particles, called by the French Mines de Bismuth Tigre. The minera bismuthi arenacea mentioned by Wallerius and Bomare belongs also to the same kind of arsenicated ores.
This semimetal is scarcely altered by exposure to the light. In close vessels it sublimes without any alteration; and if permitted to cool slowly, it crystallizes in Greek volutes. It crystallizes also more easily than any other metallic substance. Heated with access of air, its surface, when melted, soon becomes covered with a greenish-grey or brown calx. If the metal be heated at once to ignition, it burns with a small blue flame scarcely sensible, and the calx evaporates in a yellowish smoke, which condenses into flowers of the same colour. Mr Geoffroy observed, that the flowers which rise last are of a beautiful yellow colour like orpiment. By exposure to the heat of a porcelain furnace, a part of the semimetal flowed out through a crack in the vessel, and the portion which remained in the vessel formed a glass of a dirty violet colour, while the bismuth melted in contact with the external air air was yellowish. By exposure to the atmosphere the surface of this metal becomes somewhat tarnished, and its surface covered with a whitish rust. It is not attacked by water, nor does it combine with earths; but its calces give a greenish-yellow tinge to glazes. It is employed by pewterers to communicate hardness to tin; and may be used instead of lead in the cupellation of metals. It resembles lead in many respects, and is thought to be dangerous when taken internally.
Most metallic substances unite with bismuth, and are thereby rendered more fusible than before; hence it is used in the making of folder, printers types, &c., as well as pewter. When native, it is of a yellowish-white colour, and so fusible that it melts at the flame of a candle. By calcination it gains about half an ounce in the pound. This calx is said to promote the vitrification of earths, and of the refractory metallic calces more powerfully than lead, and likewise to act as a more violent corrosive on crucibles than the glass of lead itself. Hence it is preferable to lead for the purification of gold and silver, destroying more effectually the baser metals with which they have been adulterated. In all operations of this kind, where sulphur makes one of the heterogeneous matters to be destroyed, bismuth is of the greatest service, on account of its forming with sulphur an extremely fusible compound, while that of lead and sulphur proves very refractory.
Bismuth readily amalgamates with mercury, and the compound adheres to iron. On exposing the iron, thus coated with amalgam, to a combustible heat, the mercury exhales, and the greatest part of the bismuth adheres to the iron, which thus looks as if it had been silvered. If mixtures of bismuth with some other metals, particularly lead, be amalgamated, the lead becomes so thin as to pass through leather along with the mercury; but on standing, the bismuth is thrown up to the surface in form of a dark-coloured powder, the quicksilver and lead remaining united. From this property it is too often used for the purpose of adulterating quicksilver; as rendering a very considerable portion of lead intimately combined with it. One part of this metal with another of bismuth, may be united with three of quicksilver, without affecting its fluidity. The quicksilver thus adulterated is not only unfit for medicinal uses, but even for the common mechanical purposes of gilding and silvering; as the workmen find, in this case, that it leaves a leaden hue upon the gold or silver, which spoils the fine appearance of the work. If the abuse happens to be discovered, the mercury may be purified by distillation to a certain degree, though, according to Boerhaave, it is impossible ever to free it totally from a mixture of any of the imperfect metals.
This semimetal readily unites by cementation with sulphur, and melts with a more gentle heat than when alone; but on continuing the fire, a separation takes place, the bismuth falling to the bottom, and a sulphureous scoria floating on the surface. Sulphur is likewise very readily absorbed by the calx of bismuth. A curious needle-formed mass is the product of their union, in appearance exactly resembling antimony, but contracting a reddish tinge on the outside by exposure to the air. The calx cannot take up quite half its weight of sulphur.
Silver melts with the compound of calx of bismuth and sulphur in a very gentle heat into a brittle regulus. With a stronger fire gold also unites with it, forming a brittle compound, whose particles somewhat resemble an ore, with some dark and shining ones among them. Copper melts with it in a gentle heat, and the compound retains a remarkable degree of fusibility; on the addition of lead a new combination takes place; the copper and sulphur rise to the top in scoria resembling an ore, whilst the bismuth and lead unite into a regulus at the bottom. Zinc and bismuth will not unite; the former melting and burning on the surface as it does by itself. Equal parts of lead, tin, and bismuth, form a blackish sparkling compound resembling the small dried ores of lead.
The specific gravity of a mixture of bismuth and copper is exactly the mean between that of the two ingredients unmixed. With iron the compounds are specifically lighter than each of the ingredients; but with gold, silver, tin, lead, and regulus of antimony, they turn out heavier than either of the ingredients.
Bismuth reduced to powder, and applied with the white of eggs to turned wood, makes it look as if it had been silvered, after being properly dried and rubbed over with a hard polish. Some pretend that the calx of bismuth, by long reverberation, becomes red like that of lead; but this is found to be a mistake. In this case it scarcely even retains the form of a calx; for a part of the bismuth is soon revived into its metallic state by the contact of the flame. None of the destructible metallic substances is capable of being revived so easily as bismuth. The calx heated strongly in a close vessel melts into glass.
This semimetal is most commonly lodged in cobalt-ores; which, when of a high red, or peach-bloom colour, are called bismuth bloom or flowers of bismuth. It has been supposed, that bismuth communicates to glass the same blue colour with cobalt, because the drops which remain after the bismuth has been melted out, and called by the smelters bismuth-grain, sometimes produces that effect. But as no such grains or colouring-matter remains from pure bismuth, it is plain, that this property must depend on something mixed with the semimetal, and which was undoubtedly nothing but some cobalt-ore united with the bismuth.
To the same mixture we must ascribe the property which bismuth-ore has of making sympathetic ink of the same kind with that formed directly by solution of regulus of cobalt. For this purpose a tincture is to be drawn from the ore with aquafortis, and this afterwards mixed with a saturated solution of sea-salt, and infusorial, yields a reddish salt; its watery solution is the curious liquor called Green Sympathetic Ink; though there is an impropriety in calling it green, when in fact it is red. If any words are written with this ink on white paper, the characters disappear as soon as dry; but on holding the paper to the fire, they become green and legible; on cooling they disappear again, and this repeatedly any number of times. Bomare informs us, that words written with this sympathetic ink may also be rendered legible, by wetting them with a sponge or pencil dipped in an aqueous solution of lepar sulphuris. The experiments succeed best when the tincture drawn from the calcined ore is mixed with a solution of one-fourth its weight of sea-salt; this mixture is then evaporated nearly