124 
MEASUREMENT OF HIGH TEMPERATURES. 
[BULL. 54. 
This is very nearly the electric datum for the boiling point of bismuth, 
at least globules of bismuth are scattered around the walls of the cruci- 
ble. The bismuth slag is not so dark and opaque as the antimony slag, 
indeed, often quite colorless. 
Table 27. — Calibration in antimony. 
No. 
t. 
e. 
C20. 
Time. 
• 
° 0. 
Micro- 
volts. 
Micro- 
volts. 
h. m. 
22 
20 
15200 
15200 
6 10 
20 
16000 
16000 
15 
20 
17550 
17550 
20 
20 
18000 
18000 
25 
In these experiments intense white heats are produced by firing the 
furnace with two parallel blast burners, opposite in direction so as to 
blow a vortex of flame in the furnace. The crucible is finally corroded 
through, the antimony forming a corrosive opaque glaze with the clay 
of the crucible. A few small globules up as high as the flat lid of the 
crucible (Fig. 14) indicated very approximate ebullition. 
Many other experiments of the same class were made, in all of which 
the intensest degrees of white heat obtainable in the 
furnace (Fig. 14) were applied. Two and even three 
injectors were inserted, the blasts for which were fur- 
nished by a large bellows of Fletcher's pattern, run 
by a one horse power gas-engine. The data are sub- 
servient to the investigation in Chapter IV, where 
the attempt is made to calibrate the thermo-couple 
by direct comparison with the gas-thermometer. In 
this place, however, it is well to remark that definite 
data on the boiling point of antimony, bismuth, lead, 
tin, etc., will probably not be attainable by such a 
method as the present, except by heating these sub- 
stances intensely in vacuo. Such experiments I 
hope to make at an early date, using for this pur- 
pose the form of crucible, Fig. 14a, which can be 
hermetically sealed. (See Preface, page 22.) 
Thermo-electric datum for the melting point of plati- 
num. — Finally, it is interesting to contrast these high- 
temperature data with the values obtained when the 
junction of the platinum-platinum-iridium thermo- 
couple is heated by the oxyhydrogen blow-pipe to 
extreme degrees of fusion. It is necessary for this 
purpose to make a thermo-couple of very thick wires 
fig. 23. Apparatus for and to insulate them by aid of tubes of calcined 
Snum gpoiDt ° f pla ' lime. In Fig. 23 a convenient method of experiment 
(778) 
