Nitrogen Thermometer from Zinc* to Palladium. 151 



It is possible to write a cubic equation which will reproduce 

 the entire series from zinc to palladium without error greater 

 than the normal accuracy of the observations themselves. The 

 equation offered makes no pretensions to a least square solu- 

 tion with balanced residuals, but is arranged so that the great- 

 est uncertainties are found in that portion of the curve where 

 the greatest experimental error lies. The coefficients were 

 rounded off for convenience of computation. 



Cadmium to Palladium 

 E = — 169- + 7-57*-H0-0O2648* 2 — 0-0000004724* 3 



Temperature 



Cadmium 320*0° 



Zinc 418-2 



524-9 



Antimony 629*2 



854-1 



Silver 960-0 



Gold 1062-4 



Copper . 1082-6 



1206-4 

 1298-5 



Diopside 1391-2 



Nickel 1452-3 



Cobalt ._ 1489-8 



Palladium 1549*2 



6. Analysis of Metals. (By K T. Allen.) 



The object of these analyses was primarily, of course, to 

 decide whether the metals should be used or rejected for the 

 temperature scale, and those selected were examined very care- 

 fully so that in the future, when more is known about the 

 specific lowering which the various impurities produce on the 

 melting point, corrections may be made if desirable. 



The accuracy of the determinations is problematical. There 

 is of course the possibility of increased solubility of difficultly 

 soluble compounds in the comparatively concentrated solutions 

 of the metals from which the impurities have to be precipi- 

 tated, viz., 5 to 6 g. in 250 ce volume. Also, when it is neces- 

 sary to separate the bulk of the metal by precipitation from the 

 impurities, as it sometimes is, one cannot be sure that the 

 impurity sought is not occluded by the precipitates. In most 

 cases, the latter source of error is probably the more serious. 

 Only methods worked out synthetically with materials labori- 

 ously prepared could decide these questions. Large quantities 

 of metal, 25 to 100 g., were generally taken for analysis, and 







Observed — 



Observed 



Calculated 



Calculated 



Microvolts 



Microvolts 



Microvolts 



2504 



2509 



-5 



3429 



3425 



+ 4 



4470 



4466 



+ 4 



5530 



5525 



+ 5 



7929 



7934 



— 5 



9113 



9121 



-8 



10295 



10296 



— 1 



10534 



10530 



+ 4 



12000 



11988 



+ 12 



13100 



13091 



+ 9 



14228 



14215 



+ 13 



14977 



14963 



+ 14 



15439 



15424 



+ 15 



16143 



16157 



— 14 



