42 abstracts: physics 



double potentiometer, speed can be still further gained in reading 

 different instruments simultaneously. The precision of these poten- 

 tiometers exceeds that needed in ordinary pyrometry, but is useful 

 in fundamental standardization work, in calorimetry, and in numerous 

 other applications of the thermoelement. W. P. W. 



PHYSICS. — A standardized method for the determination of solidifi- 

 cation points, especially of naphthalene and paraffin. R. M. WiL- 

 HELM and J. L. Fenkelstein. Bur. Standard Sci. Paper 340. Pp. 

 12, figs. 4. 1919. 



This paper, after a brief treatment of the definitions of melting and 

 freezing points both of pure substances and of mixtures, describes a 

 method of making solidification -point determinations of naphthalene. 

 This method was recommended at a conference of Bureau of Standards 

 and U. S. Customs officials, and is based on the well-known cooling 

 curve or constant temperature method. The method is shown to be 

 applicable to the determination of the freezing points of paraffin and 

 other substances. R. M. W. 



PHYSICS. — Standardization of the sulphur boiling point. E- F. MUEL- 

 LER and H. A. Burgess. Bur. Standards Sci. Paper 339. Pp. 

 21, pis. 2, figs. 2. 1919. 

 This paper describes experiments made to complete the data which 

 are required for the standardization of the sulfur boiling point as a 

 thermometric fixed point. The precision attainable in calibration of 

 resistance thermometers at the sulfur boiling point is so much higher 

 than the accuracy of the gas thermometer determinations of the tem- 

 perature that it was considered desirable to standardize the temperature 

 corresponding to normal atmospheric pressure by definition at 444.60°, 

 and the data from which this figure was deduced are given. The rela- 

 tion between the vapor pressure of sulfur and the temperature, over 

 the pressure range from 700 to 800 mm., was determined with a pre- 

 cision of 0.0 1 ° or better. The result of this work is the formula 



t = 444.60° + o.o9io(/7-76o) — 0.000049(^-760)^ 



where t is the temperature in Centigrade degrees, assumed by a prop- 

 erly shielded resistance thermometer in the standard form of sulfur 

 boiling apparatus, and p is the pressure, expressed in equivalent milli- 

 meters of mercury at 0° and under standard gravity (g = 980.665). 

 In an appendix are given the specifications for a proposed standardiza- 

 tion of the sulfur boiling point. E. F. M. 



