152 
DE. H. T. BARNES ON THE CAPACITY FOR HEAT OF WATER 
of that year, were communicated by Professor Callendar and myself to the meeting 
of the British Association, at Dover, in September. A reprint of this communication, 
slightly modified, to contain some later determinations above 60°, was published in 
the ‘ Physical Review’ of April, 1900. 
In the present communication 1 desire to record the complete set of experiments 
obtained for the mode of variation of the specific heat of water over the entire 
range 0° C. to 100° C., feeling confident that they represent, to an order of accuracy 
approaching 1 in 10,000, the true values, and to point out the wonderful verification 
they give of the work of Regnault over the range where his experiments are the 
most trustworthy, a verification so complete that the present work may be said 
to extend over the entire range where it is possible to maintain water in the 
liquid phase. 
I desire, at this time, to record my thanks to Professor John Cox, Director of the 
Macdonald Physical Laboratory, for placing every facility at my disposal that could 
aid me in the work ; to Mr. J. W. Fraser, B.Sc., Demonstrator in Physics in this 
laboratory, for his observations on the comparisons of our 1-ohm resistance standards; 
and to Mr. G. W. Scott for his kindness in helping me prepare figures for this paper. 
I am also indebted to Messrs. Eimer and Amend, of New York, for the very 
efficient way in which they made three glass calorimeters, and the great trouble they 
took to exhaust very perfectly the vacuum-jacket connected with each one. 
Sec. 2.— General Theory of the Method of Continuous Calorimetry . 
If we have a flow of liquid, Q per second, continuously heated by an electric 
current in a fine tube enclosed in a vacuum-jacket, the walls of which are maintained 
at the temperature of the liquid flowing into the fine tube, then, when equilibrium 
has been established, 
Js Q t (6 l — Of) -f (#i — ) ht = EC H, 
where 
J is the mechanical equivalent of heat, 
s, the specific heat of the liquid, 
Cj, the temperature of the inflowing liquid, 
6 - 1 , the temperature of the outflowing liquid, 
h, the heat-loss per degree difference in temperature between the surface of 
the fine tube and the walls of the vacuum-jacket, 
EC, the electrical energy generated per second, and 
t, the time of flow. 
If the liquid be a conductor of electricity, such as mercury, then E represents the 
difference of potential maintained across the column of liquid in the fine tube, and C 
represents the current flowing through the tube. If the liquid be a non-conductor, 
