the Thermodynamic Scale of Temperature. 

 by t — tj, the third by t — t, and add 

 pv(t Y — t Q )+pv {t — tj+pv^to— t) 



Hence 

 v{h-t )+v (t- O + t^o-0 



(»-«b)tt-*o)-(»i-ro)(/-/o) 



1 



+ r + 



}* 



-:)}• 



<o-* \ 



'1 2 )' 





+ 



/J 



■'oM 



Divide by t^— 1? and transpose, 



(*i— O(t-*o)(<--*i) J"q t a,/! 1 i\i 

 (»i-t>oWi 12 + 3 W + / + IT/ J 



«! L2^o 3»o\< *o *, /./ 



From this equation we see that the expression 



t? —v 



? 1 *0 



(/ 



(t-^jt-tj 



tt 



C a ± a 2 (1 1 1\1 

 12^0^ 3v V< + f *i/J 



gives us the required corrections to the readings of the 

 constant-pressure gas-thermometer. The value of t, which 

 we require for the purpose of calculating these corrections, 

 is only known approximately ; but an approximate value is 

 sufficient for our present purpose. 



The following table gives us the corrections required for 

 the constant-pressure thermometer in the case of the gases 

 hydrogen and nitrogen. The values are calculated for every 

 10 degrees between the freezing-point and the boiling-point 

 of water, and the constant pressure is supposed to be 

 1 atmosphere. 



Tem- 

 perature. 



Correction for 



Hydrogen 

 Thermometer. 



Correction for 



Nitrogen 

 Thermometer. 



Tem- 

 perature. 



Correction for 



Hydrogen 

 Thermometer. 



Correction for 



Nitrogen 

 Thermometer. 



o°c. 











60° C. 



- -0023 



-•0202 



JO 



-•Oull 



- ooeo 



70 



-0ul9 



-•0171 



20 



-•0018 



-•0155 



80 



-•0014 



-01 20 



30 



- -0023 



-0190 



00 



- -0008 



-0069 



40 



- -0025 



-■02 10 



100 











50 



- 0025 



- 0217 









