1J SATURATED STEAM, AND O7V//.7/ VAPORS. 



and solving for the two constants by aid of the t\\o known values of 7, the 

 following equation, which is commonly used, is deduced : 



7 = t + 0.00002C + 0.0000003* 1 . 

 ^pecific heat at any temperature is. thru-fore. 



c = d ? = 1 + 0.00004* + O.OOOOOOOr*. 

 at 



The-e equations are for use with the Centigrade scale : for the Fahrenheit 

 I -iM'ii temperature may lie reduced to the Centigrade scale, and then 

 introduced ill the same rqiiationx. 



The process Of making the experiments is really a complex one; for the 

 water, in leaving the holler, has work done on it by the >team pressure in 

 the boiler, and it lias a certain velocity impress on it at the same tim< 

 again, in filtering the calorimeter, it- docs work against the atmospheric 

 pressure, and the kinetic energy of its motion is changed into heat. At 

 higher temperatures there is a double change of state; part of the water 

 in on leaving the boiler, and that steam i- condensed again in 

 the calorimeter. It i probable that the error of ncLrh-etini; the effect of these 

 several actions is Inconsiderable* 



The of accuracy to be accorded to this work is indicated by the 



fact that Regnault gives four significant figures in stating the data for 

 the calculation of the constants in the equations. 



Rowland's Experiments. A series of experiments was made by Rowland 



.'iniore. to determine the mechanical equivalent of heat, which u 

 delicate method of determining the heat of the liquid, and the specific 1. 



Tlu' apparatus used was similar to that used by Joule, with modifications 

 to give greater certainty of results. The calorimeter was of larger >i/ 

 the paddle had the upper vanes curved like the blades of a centrifugal pump. 

 to give a strong circulation "up through the centre, past the thermometer for 

 taking the temperatures, and down at the outside. The paddle was driven 

 by a petroleum engine, and the power applied was measured by makinir tin- 

 calorimeter into a friction brake, with two arms at which the tuniiuLT moment 

 was measured. Radiation was made as small as possible, and then was made 

 rminate by use of a water-jacket outside of the calorimeter. 



The experiments consisted essentially in delivering a measured amount of 

 work to the water in the calorimeter, and in noting the rise of temperature 

 produced thereby. 



The whole range covered by the experiments was from 2 to 41 C. Tin- 

 results show that 430 kilogram metres of work are required to raise one kilo- 

 gramme of water from 2 to 3 C. Assuming that the same amount will be 

 required to raise the same weight from to 1 and from 1 to 2, the follow- 

 ing table has been arranged from Rowland's final table of results: 



