A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM 203
of platinum, from 1000°. The results represented by the dotted lines were with
samples quenched at 800°. W. Stenzel and J. Weerts found that the lattice parameter
of quenched homogeneous alloys is a linear function of the composition.
W. Lewis gave for the sp. gr. of the binary alloys from platinum of sp. gr. 19-285 :
Gold
Sp. gr. .
66-7
18-378
75-0
18-613
83-3
18-812
91-67
18-835
93-75
18-918
95-8
19-089
970
19128
98-O
19-262
99-0
19-273
F. Doerinckel found that the hardness of an alloy with IO per cent, of platinum
is very like that of gold ; with 20 to 30 per cent, of platinum, the same as that of
platinum, and with over 50 per cent, of platinum, about the same as that of calcite.
The following is a selection from A. T. Grigoreeff's measurements of .Brineirs
hardness, H, of the cast alloys and of annealed alloys :
"Platinum
M \ Ann. 13-92
5
27-4
30-2
IO
33-8
34 2
20
38-2
37-2
40
83-O
77-7
6O
127-3
92-3
400
350
300}
S3
I '250
200
80
155-3
128-8
9O
99-5
1 1 J-4
The results of C. H. Johansson and J. O. Linde are summarized in Fig. 46—vide
Table TV—for alloys quenched from 900° ; for alloys with 8 to 32 at. per cent, of
platinum from 1000°, and with 40 to 96 at. per cent,
of platinum from 1175° to 1225° ; and alloys annealed
at 900°. W. Goedecke studied the change
of the hardness during the ageing of the alloys ;
and P. 13. Merica, the precipitation hardness.
C. Hatchett found that the alloy with 91*67 per
cent, of gold is malleable ; and E. D. Clarke, that
alloys with 33*3 to 50 per cent, of gold are brittle.
F. E. Carter said that the addition of gold rapidly
hardens platinum, and that the limit of workability
is attained with 10 per cent, of gold. The alloys
with gold in excess work satisfactorily, but it is
difficult to make them homogeneous. JLi. Nowack
studied the age-hardening of the alloys. W. Geibel
found that alloys with up to 20 per cent, of platinum
are easy to work, but alloys with 2O to 40 per
cent, are difficult. O. Feussner studied the hardening
of the alloy by additions of the alkaline earth
metals, magnesium, zinc, tin, iron, cobalt, and
nickel. The tensile strengths of 1 mm. wires expressed
in kgrms. are :
Platinum
Tonsil© strength
0
21-5
10
32
2O
52
J 150
1OO
—
I ^ -^-
/
A
f /
KA
/o
/i
p^
r
1OO
26O
O If
T-
\
J
J
Al
O 20 40 60 80 100
Atomic per cent of platinum
!•"""id. 46.—Brineirs MardneHH of
the I*latiivum-dold Alhiys.
3O
58
4() per cent
69 kgrms.
The elastic modulus of an alloy with 77-8 per cent, of gold was found by G. Wertheim
to be 9844 kgrms. per sq. mm., and the tensile strength to be 7-12 kgrms. per
sq. mm. ; he also found the velocity of sound in the alloy to be 6-848 when that
in air is unity. F. A. Schulze gave for the thermal conductivity, k,
Platinum
k
O
3-30
10
0-76
20
0-41
30
0-30
4O per cent.
O-26
C H. Johansson and J. O. Linde's results for the thermal conductivity of the alloys
are summarized in Fig. 47. F. E. Carter gave for BrinelFs hardness H ; Ericson's
ductility test in mm. ; and the resistance R ohms :
Gold .
22 Hard
Annealed
Ductility
R
5
. 177
98
133
IO
222
162
—
—
6O
226
174
6-9
156
7O
193
135
9-7
153
80
158
104
11-3
122
90 per cent
105
61
12-2
70