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

THE ANTIMONY PREPARATIONS AND THEIR USES. 147
as they increase the hardness and brittleness. lead is advantageous
in cast work by making the alloy more fusible, but it impairs the
colour and lustre. Arsenic induces brittleness, even in small
quantities.
The essential point in the preparation of Britannia metal is to
make the tin harder, tougher, more sonorous, and more easily polished.
The alloy gives castings as fine and sharp as those made with the
most fluid alloys of tin and lead, copper and zinc, etc. It acquires a
finer polish than alloys of tin and lead, as the latter are too soft to
sustain the action of emery and other polishing materials. Bismuth
increases the fusibility.
The best way to prepare the alloy is to melt the copper first, then
to add the antimony with a portion of the tin, and finally the remaining
tin.
Dr Karmarsh states that Britannia metal, when subjected to
rolling, has its specific gravity diminished. He explains this by
saying that the particles, under the pressure of the rolls, have a
tendency to become separated.
The following is a list of the principal alloys of tin and antimony
in commercial use :—
English metal
(Britannia metal)
, (Hobson)
Tin.
94
90
90
89-3
85-47
85
80
109 lbs.
Antimony.
, (sheet)
75 8*5
90-6 7*8
, (cast) 90*6 9-2
Queen'smetal
• 50^-75* 161-8J
88'5 7*1
, or pewter 88-5 7
English Tutania . 2577 25
German ,, .* 92
Enffestrum * 62
Ashberry metal . 80 14
Minofer
79
77*08
68-5
15
19*40
18*2
5
6
7
9*66
5
10
9 lbs.
Copper.
1
0 3
1*8
1-81
3-5 9
3 lbs
1*5
0*2
3 V 5
3*5
1
31 2
3
3 ; 3
Zinc.
3*06
1*5
0"9
...
Bismuth.
2
5*
...
8
16J-8
...
1
25
1 ...
2
2*80 i
10
i '"
Lead.
1-8
"i
8*5
161-8
Other
Metals.
3 oz.
manganese
...
brass 25
nickel 3
1
«»•
...