HOLMAN. — THERMO-ELECTRIC FORMULAE. 203 



free from systematic error. It is to be regretted that the results were 

 not more thoroughly discussed, and that neither a chemical analysis 

 nor even a statement was given to indicate the reliability of the stated 

 percentage composition of the various alloys used. For when closely 

 examined, the data seem to indicate a definite relation between the 

 composition and the emf., as was shown by a relation discovered be- 

 tween the constants in my exponential equations for the various alloys. 

 The deviations were only such as might be attributed to uncertainty of 

 composition, but as no measure of the latter was given, a statement 

 of the relations and interesting inferences from them is not warranted. 

 It is also unfortunate that an analysis, or at least a definite state- 

 ment of the percentage purity, was not given for the gold, copper, and 

 silver whose melting points were observed. The assertion that the 

 gold showed on qualitative analysis only a trace (" Spur ") of copper, 

 and the silver a " trace " of iron, is hardly definite. The value of the 

 whole work would have been enhanced by these additions far more 

 than in proportion to the comparatively small labor demanded by 

 them, and such completeness is naturally to be expected in work 

 emanating from this source. It is to be hoped that a continuation of 

 this research is in progress, and that additional high melting points 

 may be measured. 



Table III., columns one and two, quotes the interpolated mean 

 values of several comparisons expressed in international microvolts 

 and degrees centigrade. With regard to these data it should be stated 

 that below about 400° they were not supposed to be of as high ac- 

 curacy as above that point. Also, that, owing to unavoidable cir- 

 cumstances, the data below 300° were obtained with only a single 

 air thermometer bulb, and similarly those above about 1300° with 

 one bulb only, but a different one, while the data intermediate be- 

 tween 400° and 1300° are the mean of observations with the two 

 bulbs. This fact may partially account for the erratic character of 

 the residuals above 1300°, where the deviations are so great and so 

 distributed (see diagram, page 212) as to render these observations of 

 very little service. Direct comparison with the air thermometer was 

 made with one 10 per cent rhodo-platinum couple "A" only. 



The parabolic formula applied to these by Holborn and Wien, when 

 corrected as to decimal points,* is 



* The equation at both references, and stated to be in microvolts and 

 degrees, is erroneously printed as 



'■t-f{e) = 1.3.76 e - 0.004841 e2 + 0.000001378 eV 



