180 



IIoTborn and Day — Gas Thermometer at 



The comparisons of the gas thermometer and the thermo- 

 element T„ which are contained in Table XIII agree among 

 themselves exceedingly well and with the earlier comparisons 

 also. The differences, which amount to about 1'0°, are of the 

 same order of magnitude as in all the other measurements 

 made under the given conditions, the bulb with its extended 

 volume and the minute thermoelectric junction being con- 

 tained in an air bath. The highest temperatures are most 

 favorable in this respect, as the radiation acts most strongly 

 there to equalize the temperature distribution. 



Below 500° where the air bath gave place to nitre, the 

 uniformity is also greater of course. 



The conditions under which the second bulb was heated 

 were also considerably varied in order that the substantiation 

 of the earlier results might be as complete as possible. The 

 observations under "October 12" in the table, for example, 

 were made with the bulb in the same oven which had served 

 for the measurements with the first bulb, the others in a newer 

 and larger one, but with two different heating coils on the 

 different days — both wound logarithmically as described in the 

 former paper. The tubes carrying these new coils were 42 cm 

 long and 6 cm inside diameter while the older one was only 35 cm 

 long and 4 - 8 cm in diameter. The fire-clay jackets were also 

 correspondingly larger. 



Table XIII. 



Platin-iridium Bulb No. II (90Pt, lOIr ) Gas-Nitrogen. 



V =195-8'7cm 3 V s =0'904cm 3 H<,= 276-35rnm a = 0-003666 



1899 



t 



e 2 (MV) 



Obs.— 

 Calcul. 



1899 



t 



e 2 (MV) 



Obs.— 

 Calcul. 



Oct. 9 



562-1° 



4759 



0-0° 



Oct. 12 



822-9° 



7497 



— 1-5 





571-7 



4S61 



— 0-5 





822-5 



7496 



— 1-9 





573-2 



4877 



— 0-6 





1093-5 



10558 



—0-7 





829-5 



7568 



— 1-5 





1096-1 



10598 



— 1-5 





1080-9 



10423 



— 1-8 





1097-4 



10616 



-1-7 



12 



552-0 



4668 



— 1-0 



" 21 



669-1 



5836 



4-1-1 





552-2 



4670 



— ro 





917-4 



8526 



— 0-2 





5526 



4674 



— 1-0 





1063-3 



10189 



+ 0-5 





821-2 



7478 



— 1-5 











In Table XIII, t represents the temperature observed with 

 the gas thermometer, e^ the thermo-electric force of the ele- 

 ment T 2 in microvolts. The last column (Obs. — Calcul.) con- 

 tains the difference between t and the temperature in degrees 

 calculated from the curve for e v This curve will be referred 

 to again further on. 



