Adams and Johnston — Standard Scale of Temperatures. 545 



In this connection one point remains to be noted, namely, the 

 accuracy of the Reichsanstalt scale in the region 1000-1100°. 

 Holborn and Yalentiner state in one place* that the uncertainty 

 at 1000° amounts to 2 — 3° ; in another place, f in discussing the 

 reliability of their newer measurements at high temperatures, 

 they state that there is a difference amounting to 5° between 

 the older (1900) and the newer (1906) Reichsanstalt determi- 

 nations at 1100°, and continue : " The deviation from the mean 

 would still fall within the limits of error of the earlier deter- 

 minations. We consider it better, however, to attach greater 

 weight to the former measurements, because the temperature 

 gradient in the gas thermometer bulb was much smaller in the 

 earlier measurements." This may well be, for they give figures^ 

 which show that in the 1906 determinations at 1124° there 

 were differences of temperature from one point of the bulb to 

 another of as much as 346 microvolts, or about 29°. 



Summary. 



In this note a new calibration curve for copper-constantan 

 thermoelements, extending from 0° up to 360°, is given, together 

 with a series of independent measurements of the temperature 

 differences between the boiling-points of naphthalene (217*95°) 

 and benzophenone (305*9°), on the one hand, and the freezing 

 points of tin, bismuth, cadmium, and lead on the other. These 

 measurements lead to the following values of the freezing 

 points : Sn, 231*8° ; Bi, 271*0° ; Cd, 320*9° ; Pb, 327*3°. The 

 concordance of these values with those obtained by other meas- 

 urements show that the thermoelement is not inferior to the 

 resistance thermometer within this range of temperature 

 (0 — 360°). Moreover, a comparison of the gas-thermometer 

 determinations with the results obtained by means of those 

 interpolation instruments (thermoelement, resistance ther- 

 mometer, etc.), which measure not temperature independently 

 but a well-defined physical property which changes con- 

 tinuously with the temperature, affords an excellent oppor- 

 tunity, through this continuity, for the discovery of inconsis- 

 tencies in the gas thermometer measurements. The remarkable 

 concordance of the present series of thermoelectric measure- 

 ments and of the most extensive recent series of resistance ther- 

 mometer measurements (Bureau of Standards), with the recent 

 gas thermometer determinations made in this laboratory, serves, 

 therefore, as an efficient and independent check upon the trust- 

 worthiness of the present gas thermometer scale between 0° 

 and 1100°. 



Geophysical Laboratory, Carnegie Institution of Washington, 

 Washington, D. C, March 20, 1912. 



* Sitzungsber. Akad. Wiss. Berlin, xliv, 414, 1906. 



f Ann. Physik, xxii, 19, 1907. % Loc. cit., p. 8. 



