72 TABLE 41.— SECONDARY FIXED POINTS 



Temperature 

 °C (Int. 1948) 



Temperature of equilibrium between solid carbon dioxide and its vapor. . — 78.5 



( , = -78.5 + 12.12(i-l)-6.4(i-l) a 



Temperature of freezing mercury — 38.87 



Temperature of equilibrium between ice, water and its vapor (triple 



point) + 0.0100 



Temperature of transition of sodium sulfate decahydrate 32.38 



Temperature of triple point of benzoic acid 122.36 



Temperature of equilibrium between naphthalene and its vapor 218.0 



,,= 218.0 + 44.4(^-1)- 19 (i-i) 5 



Temperaure of freezing tin 231 .9 



Temperature of equilibrium between benzophenone and its vapor 305.9 



<„ = 305.9 + 48.8 (£-l)_ 21 (£-l)' 



Temperature of freezing cadmium 320.9 



Temperature of freezing lead 327.3 



Temperature of equilibrium between mercury and its vapor 356.58 



t, = 356.58 + 55.552 (-*- - 1 ) - 23.03 (-^ - 1 V + 14.0 (-£-- l) 



Temperature of freezing zinc 419.5 



Temperature of freezing antimony 630.5 



Temperature of freezing aluminum 660.1 



Temperature of freezing copper in a reducing atmosphere 1083 



Temperature of freezing nickel 1453 



Temperature of freezing cobalt 1492 



Temperature of freezing palladium 1552 



Temperature of freezing platinum 1769 



Temperature of freezing rhodium I960 



Temperature of freezing iridium 2443 



Temperature of melting tungsten 3380 



TABLE 42.— CORRESPONDING TEMPERATURES ON THE INTERNATIONAL 

 TEMPERATURE SCALE OF 1948 AND RESULTS USING WIEN'S EQUATION 



TABLE 43.— CORRECTION FOR TEMPERATURE OF EMERGENT MERCURIAL 

 THERMOMETER THREAD 



When the temperature of a portion of a thermometer stem with its mercury thread differs 

 much from that of the bulb, a correction is necessary to the observed temperature unless 

 the instrument has been calibrated for the experimental conditions. This stem correction is 

 proportional to np(T — /), where n is the number of degrees in the exposed stem, p the 

 apparent coefficient of expansion of mercury in the glass, T the measured temperature, and 

 / the mean temperature of the exposed stem. For temperatures up to 100° C, the value of 

 P is for Jena 16 m or Greiner and Friedrich resistance glass, 0.000159, for Jena 59 m , 

 0.000164, and when of unknown composition it is best to use a value of about 0.000155. The 

 formula requires a knowledge of the temperature of the emergent stem. This may be 

 approximated in one of three ways: (1) by a "fadenthermometer" ; (2) by exploring the 

 temperature distribution of the stem and calculating its mean temperature ; and (3) by 

 suspending along the side of, or attaching to, the stem, a single thermometer. 



SMITHSONIAN PHYSICAL TABLES 



