Thermodynamic Properties of Air. 13 



The experiments furnished the following values of the func- 

 tion/^) :- 



$=+100°, +19°-6, -79°*0, -104°-0, -182°-5. 

 /(d) = 3788, 3429, 2945, 2804, 2345. 



It will be remarked that the law of Tait and Avenarius is not 

 strictly fulfilled, since these numbers do not obey the law 

 of linear variation. 



Suppose now one of the solderings to be heated to 3 degrees, 

 the other to some higher temperature $'. Then the electro- 

 motive force will be: — 



E|'=Bf-B?«.yyiy)-«/t*). 



If the difference between the temperatures & and y is a small 

 one, as it was in my calorimetric experiments, where 3 '— S 

 corresponded to the small loss of temperature of the gas in 

 its passage from the heater to the calorimeter, then we may 

 write 



A*')=As)+{s'-s)^ 



and therefore 



Ei=(y-a){/w+aM|)}. 



Using the values of /(d) given before it is easy to calculate 



graphically the values of the differential coefficient *{V ■ , 

 and to construct the following table : — ° 



'g 



ft. -^ } . E 3 • h ' 



+ 100 4-42 4230 28'5 



- 79 5-22 2533 17*1 



-104 5-62 2220 15'0 



-182 6-06 1242 8*4 



The numbers headed 3^+ 1 have been obtained by division of 



