A N T I M O N Y : ITS HISTORY, CHEMISTRY, MINERALOGY ...

146 THE METALLURGY OF ANTIMONY.
antimony, in variable proportions, with smaller quantities of copper,
zinc, lead, bismuth, or other metals.
The following table, according to Long, shows the variation of the
properties of the alloys of tin and antimony, as different proportions
of the two are taken:—
Composition of Alloys.
Sb.
100-0
92*6
89-2
88*1
67*7
51*4
34*5
26-0
17*4
9*5
5-0
2*1
1-0
Sn.
7 : 4
10-8
11-9
32*3
48-6
65-5
74*0
82-6
90*5
95-0
97*9
99-0
100-0
Atomic
Formulae.
Sb
SbjoSn
SbgSn
Sb4Sn
Sb2Sn
SbSn
SbSn2
SbSn3
SbSn3
SbSn10
SbSnoo
SbSugo
SbSn100
Sn
Found.
6-713
6*739
6747
6-781
6-844
6-929
7-023
7*100
7-110
7-208
7-276
7-279
7-284
7-294
Specific Gravity.
Calculated.
6-752
6-770
6*817
6-889
6*984
7*082
7-133
7-186
7*234
7*262
7-281
7-287
Expansion.
0-013
0*023
0*036
0 045
0-055
0-059
0'033
* 0-046
0*026
0-002
0-003
Difference.
Contraction.
o-314
The addition of antimony to tin gives an alloy that possesses a
silver-white appearance, and whose melting point is higher, and hardness
greater, than the corresponding quantities of tin alone. The
brittleness increases and the malleability decreases as the proportion
of antimony increases. An alloy consisting of 80 per cent, tin and
20 per cent, antimony is sufficiently malleable to be hammered and
rolled in the cold. It is by keeping close to this proportion that the
best alloys of tin and antimony, for making pots and engravers 7
plates, are obtained. According to Chaudet, 10 parts of tin to 1
part of antimony form a perfectly ductile alloy.
The alloy is white in colour, with a bluish tint, and takes a high
polish. The amount of copper used must always be limited, as it
tends to give a yellowish tint to the appearance and diminishes its
fusibility. Good alloys show a fine-grained, jagged fracture; and if
it exhibits a crystalline structure, they either contain too much
antimony, or the union among the constituents is not intimate enough,
thus necessitating their remelting. Iron and zinc are objectionable,