226 
DR. H. T. BARNES ON THE CAPACITY FOR HEAT OF WATER 
Calorimeter A.—The first one of the set of three obtained from Germany, with 
the fine-bore tube 2 millims. in diameter. This was the first one tried in 
the trial experiments in 1897. 
Calorimeter B.—Second of the same set, with same dimensions, and used in the 
preliminary measurements of the mechanical equivalent. 
Calorimeter C.—This was the first one made by Eimer and Amend, after the 
later design. It had a 2 millims.-bore tube, and has been used for the 
greater number of the later experiments. 
Calorimeter D.—The second E and A calorimeter, with the fine-bore tube 2'8 
millims inside diameter and P 3 0 5 in the vacuum chamber. 
Calorimeter E.—The third from E and A, with the fine-bore tube 3 millims. 
inside diameter. 
The results of the experiments made to determine the relation of the heat-loss to 
the flow, are now given. They have been taken from the experiments detailed in 
Tables I., II., III., and IV. in Section 8. The results are taken from the observa¬ 
tions on two calorimeters with fine-bore flow-tubes of different sizes, the heating wire 
in the two cases being made up of either the six strands of T5-millim. platinum wire 
or the solid wire, and held central by the silk-covered rubber elastic wound round it. 
The water was therefore completely stirred in its passage through both the tubes, 
and stream-line motion avoided. 
For convenience in showing the relationship I have expressed the difference 
between the electrical and heat watts by using the value of J obtained from the 
experiment for two flows in place of 4"2 joules. In this case the value of the heat- 
loss per degree rise should come constant for all of the flows as long as the conduction 
effect is negligible. 
The first set comprises observations made with Calorimeter D at a mean 
temperature of 28° C. The flow was varied from '67 gramme per second to '25, and 
the rise of temperature was kept approximately the same by adjusting the electric 
heating current. 
Calorimeter D.—Mean Temperature, 28°'01 C. February 15, 1899. 
8 = — -00485. 
J = 4-1797. 
d6. 
Q. 
(EC - JQ d6)/cW. 
Difference from 
mean, ‘07128. 
7*5234 
•674106 
•07122 
- -00006 
7-8882 
•496655 
•07147 
+ -00019 
7-7745 
•399290 
•07130 
+ -00002 
7-9463 
•390196 
.07113 
- -00015 
8 0033 
•248234 
•07197 
+ -00069 
