74 
MR. JOULE ON THE MECHANICAL EQUIVALENT OF HEAT. 
Table IV. 
No. 
Corrected temperature 
of water. 
Gain or loss of 
heat by water. 
Corrected temperature 
of appai'atus. 
Gain or loss of 
heat by 
apparatus. 
Commencement 
of experiment. 
Termination 
of experiment. 
Commencement 
of experiment. 
Termination 
of experiment. 
1 
50-558 
50-556 
0-002 
loss 
50-565 
50-589 
6-024 
gain 
2 
49-228 
49-232 
0-004 
gain 
49-239 
49-254 
0-015 
gain 
3 
48-095 
48-106 
0-011 
gain 
48-034 
48-099 
0-065 
gain 
4 
47-416 
47-425 
0-009 
gain 
47-384 
47-429 
0-045 
gain 
5 
47-484 
47-532 
0-048 
gain 
48-103 
GO 
0-321 
loss 
6 
47-429 
47-439 
0-010 
gain 
47-703 
47-610 
0-093 
loss 
7 
47-624 
47-637 
0-013 
gain 
47-870 
47-790 
0-080 
loss 
8 
47-705 
47-712 
0-007 
gain 
47-915 
47-859 
0-056 
loss 
9 
47-685 
47-702 
0-017 
gain 
47-891 
47-837 
0-054 
loss 
10 
48-733 
48-793 
0-060 
gain 
49-498 
49-112 
0-386 
loss 
11 
49-689 
49-694 
0-005 
gain 
49-946 
49-842 
0-104 
loss 
12 
48-191 
48-168 
0-023 
loss 
47-972 
48-134 
0-162 
gain 
13 
48-101 
48-119 
0-018 
gain 
48-310 
48-254 
0-056 
loss 
14 
49-413 
49-390 
0-023 
loss 
49-249 
49-413 
0-164 
gain 
15 
49-243 
49-241 
0-002 
loss 
49-343 
49-318 
0-025 
loss 
16 
49-103 
49-103 
0 
49-172 
49-172 
0 
17 
46-991 
46-902 
0-089 
loss 
46-204 
46-923 
0-719 
gain 
18 
46-801 
46-814 
0-013 
gain 
47-139 
46-953 
0-186 
loss 
19 
46-624 
46-624 
0 
46-652 
46-652 
0 
20 
46-266 
46-158 
0-108 
loss 
45-369 
46-167 
0-798 
gain 
Mean... 
0-0016 loss 
0-03155 gain 
By adding these results to those of the former table, we have a gain of temperature 
in the water of 3°T3305, and a loss in the apparatus of 20°'33155. Now the capacity 
of the can of water was estimated as follows : — 
Water 141826 grs. 
15622 grs. copper as water . . 1486 grs. 
Thermometer and stirrer as water 118 grs. 
Total .... 143430 grs. 
S*T3305 
Hence 20 - 3315 5 ^ 143430 :=22I02‘27, the capacity of the apparatus as tried. The 
addition of 21 ‘41 (the capacity of 643 grs. of mercury which had been removed in 
order to admit of the expansion of 70°) to, and the substraction of 52 grs. (the 
capacity of the bulb of thermometer C, and of the iron wire employed in suspending 
the apparatus) from this result, leaves 2207 T68 gi’S- of water as the capacity of the 
apparatus employed in the friction of mercury. 
The temperature 2°'491218 in the above capacity, equivalent to 1° in 7*^5505 lbs. 
of water, was therefore the absolute mean quantity of heat evolved by the friction of 
mercury. 
