OF GUN-METAL. IO9
os the figures, are in the triplicate ratio of the penetrations,marked in the first column ; and the relative hardness of therods are expressed in the inverse ratio of these holes;.forexample, the hardness of the bronze A is to the hardness ofthe bronze F as 173 to 51.
Result of experiments made in 1759 to compare the rela-tive hardness of the following metals:
The relative Penetrations of the punchinto the Rods.
First Column .
Fine tin of England —
Pure copper of Germany —Small pieces of copper coinBrass of Germany, malleable when coldA mixture of 100 parts of copper, 12 1of tin, and 2 of zinc, the zinc be- 5ing previously mixed with the tin JA mixture of 100 parts of brass and ?12 of tin. —— — 5
92
66
58
54 -
42
35
Effects express-ed by therelative sizesof the holesmade by thepunch.
Second Column.
1216
450
301
246
11668
Bronze formed of good Materials in the following Proportions.
Copper.
Tin.
Brass
I st. Col. 2 d. CdL
rA
100
25
32
5 i
B
100
20
35
66
C
' ICO
16
-
37
78
D
100
14
40
100
E
IGO
12
42
116
F
100
8
48
173
G
100
24
IOO
37
78
Different Mixtures. <
H
K
100
100
20
16
5
28
34
36
62
73
L
100
14
8
37
78
M
100
12
6
40
100
N
ICO
10
12
42
116
P
100
9
20
44
133
Q.
100
8
28
47
162
R
100
5
20
49
184
IT
100
2
20
52
220
30.
We