JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. II, JUNE 19, 1912 No. 12 



PHYSICS. — A note on the standard scale of temperatures between 

 200° and 1100°. L. H. Adams and J. Johnston, Geo- 

 physical Laboratory. 



The original measurements recorded in this note were made 

 over a year ago in connection with another investigation; they 

 determine the freezing points of the four metals, tin, bismuth, 

 cadmium and lead, in terms of the boiling points of naphthalene 

 and benzophenone. 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 ther- 

 mometer as an accurate temperature measuring device within 

 the temperature range in question. In addition, it is shown that 

 the most thorough and most extensive series of resistance ther- 

 mometer 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 ther- 

 mometer measurements 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, 1 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?56) identical with the gas thermometer determinations. 



The calibration of the thermoelements has already been described 2 

 but the account there given must be amplified by the following addi- 

 tions and corrections, which are rendered necessary by the slight changes 



Namely, the boiling points of naphthalene and benzophenone, and the freez- 

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

 2 Am. J. Sci. 31: 501-17. 1911. 



275 



