534 Adams and Johnston — Standard Scale of Temperatures. 



Art. XLIY. — A Note on the Standard Scale of Tempera- 

 tures between W0° and 1100° ; by L. H. Adams and J. 

 Johnston. 



A year ago, at the time when the original measurements 

 recorded in this note were completed, there was an outstand- 

 ing uncertainty of about 1° in the temperature scale around 

 400°; at the present time, by reason of the concordant results 

 obtained in the best series of gas thermometer determinations 

 within this region — those recently published by Holborn and 

 Heiming* and Day and Sosmanf — this uncertainty is not more 

 than 0*1°, and is probably less than this, at temperatures up to 

 500°. The definite establishment of the temperature scale ren- 

 ders the conclusions presented in this note to some extent 

 supererogatory ; nevertheless, it has been thought worth while 

 to present them, as, at the least, they serve to confirm those 

 expressed in the preceding paper. 



In what follows, we present independent thermoelectric 

 measurements at the boiling points of naphthalene and benzo- 

 phenone and of the freezing points of four metals — tin, bis- 

 muth, cadmium and lead ; the agreement of these results with 

 the best resistance thermometer measurements of the same 

 fixed points shows that the thermocouple is not inferior to the 

 resistance thermometer as an accurate temperature-measuring 

 device within the temperature range in question. Moreover, 

 we propose to show that the most thorough and most extensive 

 series of resistance thermometer measurements — those of 

 Waidner and Burgess, made at the Bureau of Standards — are 

 also in remarkable agreement over the whole range of 

 temperature (up to 1100°) with the gas thermometer measure- 

 ments of Day and Sosman, when they are expressed in the 

 same scale. At the same time this comparison shows that, if 

 we consider all of the points, % excepting sulphur, to be fixed 

 by the gas thermometer work, and on this basis set up an 

 interpolation formula and calculate therefrom the boiling 

 point of sulphur, the resistance thermometer measurements 

 lead to a value (444-55°) identical with the gas thermometer 

 determinations. 



Calibration of the Thermoelements. 



In connection with another investigation! it became neces- 

 sary to calibrate carefully some copper-constantan therm o- 



* Ann. Physik, xxxv, 361-74, 1911. f Preceding paper. 



\ Namely, the boiling points of naphthalene and benzophenone, and the 

 freezing points of tin, cadmium, zinc, antimony, silver and copper. 

 § This Journal (4), xxxi, 501-17, 1911. 



