Chav. II. COMPOSITION" AND USE OF MINERALS. 655
Antimony is found native, and its principal ore is the sulpliuret; the most common iscrystallised into four and six-sided prisms; it is of a white colour, brittle, and of a crys-talline texture; fuses at about SOO , and its specific gravity is 6*712; it is prepared fromthe sulphuret by heating it in a crucible with iron filings, when a sulpliuret of iron andthe metallic antimony are formed.
The composition of the oxides has been differently stated, and it seems that there arethree distinct varieties. The oxygen in the protoxide is to that of the peroxide as 1 *5 to2-5, and that in the three oxides one atom of antimony is united with 1*5, 2, and 2-5 ofoxygen.
Sulphuret of antimony is artificially produced by fusing the metal with sulphur; it hasa dark grey metallic colour, and a specific gravity of 4*36.
Antimony - - 1 - 65 - 73
Sulphur - - - 1£ - 24 - 27
1 89 100
Bismuth is found native, combined with oxygen, arsenic, and sulphur ; it occurs crys-tallised into cubes and octohedra; it is a brittle white metal with a reddish tint ; its specificgravity is 9‘85; it is fusible at 496°, and always crystallises when cooling.
Protoxide of bismuth is obtained by dissolving bismuth in nitric acid, which isprecipitated by dilution with water, and heated, when dry, to a dull redness.
Uismuth - - - 1 - 72 - CO
Oxygen - - 1 8 - JO
1 80 ICO*
Chloride of Bismuth , or Butter of Bismuth , is of a grey colour, and fuses at 480° ; whenexposed to air it deliquesces.
Bismuth - - - 1 - 72 66-6
Chlorine - - - 1 - 36 - 33-4
1 103 1000
Alloys of bismuth arc formed with gold, platinum, and silver. Fusible metal is a com-pound of 8 of bismuth, 5 of lead, and 3 of tin, which liquefies at the temperature ofboiling water. Soft solders contain bismuth.
Manganese has a powerful affinity for oxygen, attracting it from air and water; in itsappearance it resembles iron. It is a hard grey metal, brittle and granular ; the specificgravity of which is 6'8.
Oxide or Protoxide of Manganese : —
Manganese -
.
- 1
-
28
-
77-75
Oxygen
-
- 1
-
8
-
22-25
1
36
100-00
Manganesic Acid .—When peroxide of manganese (which is i of manganese and 2 ofoxygen) and nitre are heated, a compound is obtained called Chamelion. It consists ofmanganesious acid and potassa, gives in water a green-coloured solution, which becomespurple and red by exposure to the air ; the red colour is formed by the manganesiouscompound attracting oxygen.
Chromium . — In a metallic state its colour resembles that of iron; it is brittle, difficultof fusion, and is not easily acted upon by the acids. Its specific gravity is 6.
Protoxide of Chromium is of a green colour, and when fused with borax produces thatused in porcelain and enamel painting; the emerald receives its tint from it.
Chromium - - - 1 - 28 - 70
Oxygen - - -1^-12-30
1 40 100
Chromate of Lead , in its native state, is of a deep orange colour, approaching to redness,but when reduced to a fine powder is yellow; its primitive crystal is an oblique prism.Its specific gravity is 6. In an anhydrous state it consists of
Oxide of lead - - 1 - 112 - 68-29
Chromic acid - 1 - 52 - 31-71
1 164 100 00