BARUS.] 
DEGREE OF CONSTANT TEMPERATURE. 
73 
Table 4. — Constancy of temperature in earlier forms of the zinc boiling-point apparatus ; 
time series — Continued. 
Date. 
Time. 
h. 
No. of 
thermo- 
couple. 
' £20. 
T 3 . 
T m . 
Remarks. 
Feb. 2, 1S84 
h. on. 
3 15 
0.00 
18 
7930 
768 
818 
Approaching ebullition. 
19 
0.07 
18 
8100 
780 
833 
25 
0.17 
18 
8420 
802 
8G0 
30 
0.25 
18 
8740 
825 
884 
35 
0.33 
18 
9110 
851 
915 
Ebullition. 
40 
0.42 
18 
9170 
856 
920 
56 
0.68 
18 
9190 
857 
S21 
4 19 
1.07 
18 
9220 
860 
924 
The second part of this table (Jan. 30) is complete. The third (Feb. 2) 
and the first (elan. 20) part together make a series, showing in all cases 
the rise and fall of temperature at the inception and at the close of the 
distillation. The criterion of the occurrence of the boiling point is con- 
stancy of temperature ; for the furnace is sufficiently hot to superheat 
the crucible when the charge of zinc is low or nearly distilled over as 
the second part of the table shows. An early stopping or a late begin- 
ning of the experiment is the result of accidents, which for the difficulty 
of the experiments are not infrequent. 
As distinguished from the above data the following results are all ob- 
tained with very large apparatus, a "number 60" graphite crucible of 
Messrs. Dixon, with a capacity sufficient to hold 60 pounds of zinc, being 
used for the experiments. The apparatus and furnace have already 
been described and it will therefore suffice to summarize the data. This 
is done in the following very complete tables on a plan identical with 
the preceding. 
Table 5. — Constancy of temperature in thejater form of zinc boiling-point apparatus ; 
time series. 
Date. 
Time. 
h. 
No. of 
thermo- 
couple. 
620. 
*. 
T v , 
Remarks. 
h. m. 
Apr. 15, 1884 
2 15 
0.00 
18 
7980 
770 
8:32 
Charge M pounds. 
26 
0.18 
18 
8540 
812 
868 
38 
0.38 
18 
9110 
852 
915 
50 
0. 58 
18 
9550 
882 
952 
53 
0.63 
18 
9710 
893 
965 
3 05 
0.83 
18 
9940 
910 
983 
10 
0.92 
18 
10020 
915 
990 
Apr. 18, 1884 
2 08 
0.00 
18 
9500 
880 
947 
Charge 20 pounds. 
15 
0.12 
18 
9530 
882 
950 
20 
1.20 
18 
9640 
890 
957 
30 
0.37 
18 
9807 
901 
971 
Furnace fired. 
40 
0.53 
18 
9960 
911 
985 
50 
0.70 
18 
9930 
.909 
982 
(727) 
