.142 Mr. J. Rose-Innes on the Practical Attainment of 

 Hence 



■>-**.-%<*-« = <«,-«{«.+ Jg + 1) + ?(£ + A + £)}, 



The term v gives us the u uncorrected estimate " of 



£ on the constant-pressure thermometer ; we may obtain the 



value of this quantity for hydrogen and for air by using 

 Regnault's experimental results. The remaining terms 



constitute the necessary correction to the value of £ ; and we 

 may calculate the value of this correction since a , a ly and a 2 

 are all known. We thus obtain the following results : — 



Hydrogen . . . 

 Air 



Uncorrected estimate 



of temperature of 



freezing-point. 



273-13 

 272-44 



Correction. 



-•13 

 •72 



Corrected 

 estimate. 



273-00 

 273-16 



The final results do not differ sensibly from those obtained 

 by Lord Kelvin for the same gases (see Reprinted Papers, 

 vol. iii. p. 177) ; the first column of figures is taken from 

 Lord Kelvin's paper (loc. cit.). 



We will next discuss the corrections needed in order to 

 convert the readings of the constant-pressure thermometer 

 into temperatures on the thermodynamic scale. 



Let us take the equation 



Employing the same notation as before we may write 

 Multiply the first of these equations by fi— ^ the second 



