246 



Tables 223 and 224 



TABLE 223.— Standard Calibration Curve for Copper — Constantan Thermoelement, 

 Temperatures Below 0°C 



TABLE 224.— Melting Points of Some Purified Salts, 400-1300°C 



(Roberts, some new standard melting points at high temperatures, Phys. Rev., 2d ser., 23, 386, 1924, which 



see for technique of their use.) 



Potassium dichromate 397-5°C 



45 KC1 + 55 Na 2 S0 4 by wt 517.1 



30.5 NaCl + 69.5 Na 2 S0 4 bywt. 627.0 

 Potassium chloride 770.3 



Sodium chloride 800. 4°C 



Sodium sulphate 884.7 



Potassium sulphate * 1069.1 



Dicalcium borate (CaoBjOs) .... 1304 



* Potassium sulphate has sharp inversion point at 583° ± 1. 

 Smithsonian Tables 



