[ 199 ] 



V. The Specific Heat of Water and the Mechanical Equivalent of the Calorie 



at Temperatures from C. to 80 C. 



By W. R. BOUSFIELD, .17". .4., K.C., and W. ERIC BOUSFIELD, B.A. 



Communicated by Kir JOSEPH LARMOR, Sec. R.S. 



Received January 19, Read February 23, 1911. 



CONTENTS. 



Section Page 



1. Introduction 199 



2. Description of the calorimeter 205 



3. The electrical arrangements 210 



4. The primary standards 210 



5. Calibration of the mercury thermometer-resistances 212 



6. Considerations in reference to working standards of resistance for carrying heavy currents . 216 



7. Heating due to obturator, stirring, <&c 220 



8. Continuous-flow experiments 223 



9. Point-to-point experiments. General description 226 



10. Determination of mean capacity of calorimeter 228 



11. Value of J, S M for distilled water 229 



12. Specific heat of glass 230 



13. Determination of mean values of J for various intervals 233 



14. Deduction of values of J for various temperatures 235 



15. Comparison of results with former determinations 237 



Appendices A, B, C, D, E, F, G 244 



1. Introduction. The work described in this paper started from the researches upon 

 the properties of aqueous solutions, which have occupied one of us for some years 

 past.* In the course of this work it had been found that the measurement of various 

 physical properties of solutions, including density, conductivity, and viscosity, at 

 various temperatures and various concentrations, threw considerable light, not only 

 on the constitution of solutions, but upon that of water itself and upon the amounts 



* See BOUSFIELD and,Lo\VRY, 'Phil. Trans.,' A, vol. 204, p. 253, 1905; BDUSFIELD, 'Zeit. fur Phya. 

 Chem.,' vol. 53, p. 257, 1905; BOUSFIELD, 'Phil. Trans.,' A, vol. 206, p. 101, 1906; BOUSFIBLD and 

 LOWRY, 'Trans. Farad. Sic.,' vol. 3, p. 123, 1907; BOUSFIELD and LOWRY, 'Trans. Farad. Soc.,' vol. 6, 

 p. s:>, 1910. 



VOL. CCXI. A 475. 30.5.11 



