feAkUS.j 
CALIBRATION OF ELECTRICAL PYROMETERS. 
10? 
stant temperature may be much increased. It has been stated that in 
the data of Table 13 the variations of boiling point, and not the abso- 
lute value of the boiling point, is the point of consideration. 
Exploration for constancy of temperature; sulphur. — From the nature 
of the case, the calibration with sulphur is more difficult, and calls for a 
more careful examination. Hence series of data are drawn up in Table 
14, both for gentle and for violent ebullition. The condition of con- 
stancy of the center of the zone of constant temperature is also tested 
by a special thermo-couple, inserted from time to time during the prog- 
ress of the measurements. In the first part of Table 14 the surface of 
ebullition is at 12 cm above the bottom ; in the remaining parts about 
8.5 cm from the bottom. No carbonic-acid or other gas is introduced into 
the tube, and ebullition probaby takes place in S0 2 gas, formed from S 
vapor and the oxygen of the tube. To produce very violent ebullition 
the copper gauze surrounding the sulphur tube was heated even to red- 
ness. As before, the variation of T, and not the absolute value of the 
boiling point, is the chief consideration. 
Table 14. — Constancy of temperature along axis of boiling tube. Sulphur. T=449°. 
Height above 
bottom of tube. 
t. 
, 
T. 
Time. 
Remarks. 
Cm. 
°0. 
Micro - 
volts. 
°0. 
fl5 
In vapor. ■I 14 
1 13 
r 11 
10 
In liquid, s 
15 
3050 
339 
1 
15 
4038 
433 
15 
16 
4203 
4226 
418 
451 
16 
16 
4273 
4157 
455 
445 
i Burner at 10 cm . Liquid surface 
( at 12™'. 
Is 
16 
■ 3394 
373 
1 
h. m. 
12 
16.6 
4206 
449.5 
11 30 
12 
17.2 
4198 
449.2 
12 10 
t 
f 13 
19.0 
3923 
398.9 
2 15 p.m. 
1 
11 
In vapor. { 
19.0 
19.0 
4498 
4517 
445.0 
446.5 
[\ 
19.0 
4545 
448.5 
r 8 
19.0 
4629 
455.3 
i Mild ebullition. Liquid sur- 
face at 8.5"». 
1 7 
19.0 
4651 
456.8 
1 6 
In liquid. { 
19.0 
19.0 
4577 
4078 
451.4 
411.9 
I 3 
19.0 
19.0 
3448 
2779 
359. 3 
301.0 
r 13 
19.0 
3886 
305. 9 
3 15 
1 
J 11 
In vapor, i 
I 9 
19.0 
19.0 
4487 
4506 
444.0 
445. 4 
19.0 
19.0 
19.0 
4545 
4587 
4643 
448.6 
452.1 
456. 5 
Mild ebullition. Liquid at 
8.5 cm . 
In liquid. <( 6 
19.0 
4509 
445.8 
1 5 
19.0 
3988 
403.8 
h 
19.0 
3221 
339.6 
(7G1) 
