248 
DR. H. T. BARNES ON THE CAPACITY FOR HEAT OF WATER 
Table XVIII.—Summary of Results of Observations— continued. 
Number 
and date. 
Jacket. 
Temp. ° C. 
Temp. rise. 
d.9, c C. 
Flow Q. 
gm./sec. 
Product. 
4-2 Q d6. 
Watts. 
EC. 
DiS./dd. 
D. 
Results. 
d, h, J. 
Serie 
s VIII. Calorimeter C 
Solid Cone 
uetor. Then 
ammeter E, T 
V. Box II.- 
—continued. 
LII. 
69 °85 
8-°3152 
•622088 
21-7257 
22-3864 
•07947 
d= - -00189, 
Feb. 28, 
69-85 
8-3226 
• 620830 
21-7011 
22-3672 
•08044 
h= + -08469, 
1900. 
69-86 
8-4472 
•385739 
13-6853 
14-3733 
•08146 
J= 4-1920, 
69-86 
8-4893 
•383723 
13-6816 
14-3761 
•08181 
at 74’-05 C. 
LIII. 
87-42 
8-2361 
•645077 
22-3142 
23-1450 
•10088 
d= + -00042, 
Mar. 10, 
87-41 
8-2513 
•642851 
22-2783 
23-1161 
• 10155 
h= + -10011, 
1900. 
87-43 
8-2768 
•402934 
14-0069 
14-8450 
•10130 
J= 4-2017, 
87-43 
8-3168 
•400935 
14-0049 
14-8398 
•10030 
at 91°‘55 C. 
LIV. 
76-12 
8-5262 
•617742 
22-1213 
22-8806 
•08894 
d=- -00117, 
Mar. 17, 
76-12 
8-5570 
•615198 
22-1099 
22-8747 
•0S938 
li= + -09218, 
1900. 
76-12 
8-5224 
•388311 
13-8992 
14-6692 
•09036 
J= 4-1951, 
76-12 
8-5433 
•387095 
13-8897 
14-6603 
•09021 
at 80’ ■ 38 C. 
LY. 
63-84 
8•6883 
•387767 
14-1499 
14-8324 
■07856 
d= - -00262, 
Mar 21, 
63-84 
8-6760 
•387527 
14-1212 
14-8029 
•07858 
h = + -08283, 
1900. 
63-82 
8-8222 
•604663 
22-4047 
23-0757 
•07606 
J= 4-1890, 
63-82 
8-8494 
■601956 
22-3732 
23-0488 
•07634 
at 68°-21 C, 
Each single line in the above table represents the mean results of the observations 
of temperature and potential difference taken, as explained and illustrated by the 
specimen tables of observations, during a period of 15 minutes, for which the corres¬ 
ponding value of the flow was measured. In nearly all cases the observations were 
repeated during a second period of 15 minutes under conditions as nearly as possible 
the same, except for a slight diminution of the flow, due to the fall in the water 
level. The order of accuracy of the readings can be estimated by comparing the 
corresponding values of D for the two similar flows. The two values of D should 
agree, except that the falling-off of the flow tends to make the second value in each 
case slightly the larger when d is negative. In comparing the values it must be 
remembered that 3 in the fifth place of D corresponds to only 1 part in 100,000, with 
a heat supply of 24 watts and a rise of 8°. The differences seldom exceed 1 in f 0,000, 
whereas with the method of mixtures it is very difficult to obtain an order of 
agreement of 1 in 1,000 in repeating an experiment under identical conditions. 
The values of d as directly measured and expressed in the different series just 
given, I have plotted in fig. 17. From the smooth curve drawn so as to include 
the observations, I have taken the following values of d and calculated the 
corresponding values of J. These are summarized here (p. 250). The values of J 
are, of course, in absolute measure, and the values of d in terms of a thermal 
unit equal to 4 - 2000 joules, which occurs at 9° C. and 88 '5 C. The mean value of 
