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ANTIMONY.— Uses in the Aets.
that the workman, while operating on one side, is notinconvenienced by the fumes of the other, o o areorifices several inches in height, by which the cylin-Fig 9 _ dors may be
reached fromthe front andback part ofthe furnace byconical open-ings, such as p,in the walls; theopenings, o o,are closed dur-ing the workingwith clay stop-pers, n n, seenin the preced-ingfigure, whichare removed atthe end of anoperation. a'and b' b' areiron and wood-en beams andbands to bracethe chimneys.</ c' are conical arches on both sides of the furnace,closed with well-fitting plates, Of d '; through thesethe interior of the furnace may be examined, andrepairs made when required.
Each cylinder is charged with 490 lbs. of ore, pre-viously warmed on the arch, the coarsest and richestof which is placed at the bottom of the cylinders.As soon as the melting of the ore is completed, theimpurities remaining are withdrawn through the open-ings, o o, and a fresh charge is introduced. The tri-sulphide of antimony produced should have a bluishcolour; if it possesses a reddish appearance, it is indi-cative that too great a heat has been applied. Whenthe iron receivers are three-quarters full, they aredrawn out and allowed to cool, and the lump of crudeantimonious sulphide is removed. Fresh charges areput in every three hours, and about 1 cwt. of thetrisulphide is obtained at each process, when the fur-nace is in good working order, On an average, thecylinders last about twenty days.
It is of extreme importance that the heat be nottoo great, since at a white heat antimony is com-pletely volatilized. Nor should the ore be too finelypulverized, as in this case the melted sulphide cakestogether with the gangue, and is very difficult toseparate. The residues always contain from 10 to12 per cent, of antimony, partly in the form of tri-sulphide,'partly as trioxide.
The product of the preceding operations is nextroasted in a reverberatory furnace to expel the wholeof its sulphur, and to produce instead the trioxide ofthe metal; the latter is subsequently reduced bymixing it with about 20 per cent, of charcoal, saturatedwith a strong solution of carbonate of soda. Accord-ing to Bertiiier, 70 per cent, of good metal may beprooured from the ordinary product of fluxion of thecrude sulphide, when mixed with CO parts of iron
scales from the hammer or rolling mill, 45 to 50 ofcarbonate of lime, and 10 to 12 of powdered charcoal,and the mixture heated to fusion in the ordinary way.Iron is often found in considerable quantities in theantimony procured from this mixture ; ,and therefore,unless subsequently purified, it cannot, in manyinstances, be advantageously employed.
Uses in the Arts. —Antimony is chiefly used asan ingredient in making alloys, such as type-metal,Britannia-metal, plate-pewter, and various others.The typefounder uses two alloys of antimony, lead,and tin ; the one composed of—
Tea lead, ... 751 (Tea lead,.... 70
Antimony,.. 20 V and the other K Antimony,... 25Block tin, .. 5) (Block tin,— 5
100 100
Stereotype metal is formed of
Antimony,. 18 “
Block tin,. 3 “
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The best Britannia-metal is composed of:—
Copper,. 3 “
Antimony,. 10 “
Common Britannia-metal:—
Copper,. 3 “
Antimony. 9 “
Britannia-metal for Castings:—
Tin,. 210 lbs.
Copper,. 4 “
Antimony,. 12 “
Britannia-metal for Lamps:—
Tin,. 300 lbs.
Copper,. 4 “
Antimony,. 15 “
A higher proportion of antimony is sometimesused. Copper is added to give colour. The chiefuse of antimony in making stereotype plates is, thatbesides hardening them, it causes expansion of thealloy in cooling, and as the cooling next the type islatest, the expansion causes the metal to fill everyinterstice, and beautifully sharp casts result. Nearlyevery manufacturer uses different proportions of anti-mony according to the quality of his tin. The usualpractice is to test a small quantity of the tin withantimony, before casting on the large scale.
Antimony imparts a peculiar beautiful red colourto copper, varying from rose red, with little antimonyand much copper, to crimson and violet when theproportion of the metals more nearly approach equal-ity. For this reason antimony is sometimes addedto brass to improve its colour.
Antimony is used for the preparation of concavemirrors. It gives a finer texture to the mass, onwhich account it takes a better polish. It is also aningredient of bell metal, being supposed to increasethe clearness and strength of the sound, besides im-proving the colour of the bells.