BARUS.] 
DEGREE OF CONSTANT TEMPERATURE. 
79 
From this table it is expedient to select the mean values for each 
element, and then to arrange the alloys in a series of the kind described 
on page 80. This has been done in Table 7, where, in addition toe 20 930 , 
the constants a and Z>, derived from the last definite calibration, are in- 
serted (microvolts). The interval of calibration for a and b is only 0° 
to 400°, as has been stated. Knowing, therefore, c, a, and b we are able 
to compute T 6 , or the exterpolated value of the zinc boiling point, to 
which special reference will presently be made. The figures for e in 
parenthesis will be referred to in Chapter II. 
Table 7. — General summary of results. 
Series 
No. 
No. 
Description of element. 
How, where, or by 
whom made. 
Mean e. 
a. 
b. 
T„ 
r 
17 
Pt (h); Pt-Ir, 20%; annealed. 
Paris metallurgists.. 
c (9412) 
I S285 
J 7. GO 
+ 0.00390 
861 
18 
do 
do 
r (9345) 
i 916(5 
I 7.60 
+0.00385 
857 
19 
Pt (h); Pt-Ir, 5%; annealed .. 
....do 
C (2801) 
I 2823 
i 3. 07 
-0.00010 
966 
9 
do 
....do... 
c (2869) 
I 2827 
€ (9453) 
I 9230 
I 3. 05 
\ 7 - G0 
—0. 00009 
+0. 00393 
973 
I< 
22 
Pt (h); Pt-Ir, 20%; annealed.. 
....do 
856 
23 
Pt (h); Pt-Ir, 5%; annealed .. 
....do 
r 2829 
X (2885) 
\ (2. 97) 
(+0.00047) 
970 
24 
Pt (h); Pt-Ir, 2% ; annealed .. 
Pt-Ir 596 fused into 
Pt (s) in proper 
ratio, at Lab., OH2 
791 
1.88 
—0. 00150 
(*) 
I 
blast. 
n S 
25 
Pt (s); PtPd, 3%; annealed.. 
r Pd alloyed to Pt (a), 
1 at Lab., O H-blast. 
i m 
i 2297 
0.287 
+0. 00119 
797 
26 
Pt (8); Pt Pd, 10% ; annealed. . 
0.975 
+0. 00273 
760 
f 
1 
mi 
i 
I 
27 
28 
29 
Pt-Ir, 5%; Pt-Ir, 1096; an- 
nealed. 
Pt-Ir, 5%; Pt-Ir, 15%; an- 
nealed. 
Pt-Ir, 5% ; Pt-Ir, 20% ; an- 
nealed. 
] Pt It 5% and Pt 
j Ir 2096 wires 
S fused together in 
proper ratio, at 
Lab., OH 2 blast. 
( 2941 
J 5030 
1 C449 
t 
2.36 
3.89 
4.51 
+0.00152 
+0. 00268 
+0. 00398 
826 
834 
835 
-1 
30 
31 
Pt (com.); Pt(com)-Ni, 5%; 
annealed. 
Pt (com.); Pl(com)-Xi, 2%; 
] Ni alloyed to Pt 
} (com.), at Lab., 
J OH2 blast. 
f 7121 
1 
| 3744 
I 
8.43 
4.56 
+ 0.00050 
+0. 00005 
825 
833 
f 
32 
Pt (com.); Pt(com.)-Ir, 3%; 
1 
f 1998 
1.98 
+0. 00052 
844 
v. 
33 
34 
annealed. 
Pt (com.); Pt(com.)-Ir, 596; 
annealed. 
Pt com.); Pt(com.)-Ir, 79^; 
annealed; 
1 Ir (com.) alloyed to 
} Pt (com.), at Lab., 
OH2 blow-pipe. 
J 
3981 
| 533G 
I 
3.64 
4.70 
+0. 00147 
+0. 00207 
833 
842 
* Imaginary. 
Series of alloys. — Having reached this stage of the inc 
luiry, we 
are 
prepared, so far as the set of data at present in hand go, 
to brin£ 
; the 
considerations back to the probable properties of the z( 
jro eleim 
3nts, 
(733) 
