Thermo-electric Interpolation Formulae. 



481 



Table VIII. gives the constants for the exponential equation 

 (those for the Avenarius may be found in Soil's article), the 

 mean deviations ( = data— equation) for each series, and the 

 mean percentage deviations ( = 100 8/e). (See remark as to 

 use of e under " Barus Data.") Table IX. groups the per- 

 centage deviations under their nearest values of t for exhi- 

 biting their systematic character. The fact that the experi- 

 mental method brought the observations all very nearly to 

 the respective temperatures t given in the table renders this 

 grouping possible. I have taken the liberty of correcting a 

 few obvious numerical errors, and of dropping a very few 

 values evidently containing a mistake. 



It may, perhaps, not be out of place here to caution those 

 who would make use of NolFs data to their full accuracy that 

 his original, and not his interpolated, numbers should be 

 resorted to. The approximate linear interpolation which he 

 has employed is not as accurate as his experimental data 

 demand. 



The logarithmic equation applied to the Cu-Hg couple as 

 typical of the Noll data yields 



SS«=2-57434 P*"; 

 or 



log 2o e=l-2250 log £+0-410665. 

 The residual^ to this expression are given in Table IX. 



Table IX. 

 Avenarius Equation. — Data minus Equation in Per Cent. 





15°. 



57°. 



100°. 



138°. 



181°. 



198°. 



217°. 

 



Au-Hg 



-010 



-040 







+0-05 



4-0-60 



+0-90 



Ag-Hg 



-013 



+ 20 







+0-21 



-0-50 



-1-30 







Ni-Cu 



-0-26 



-0-15 











-0-22 



-0-31 



-117 



Er-Cu 





-0-10 







4-0-20 



4-0-17 



4-0-35 







Za-Hg 





-003 







+0-09 



4-0-41 



4-0-40 







Pb-Cu 





-0-03 







-0-11 



4-0-12 



-0-04 







CS-ffg 



+002 



-0-16 







+001 



+0-15 



+0-38 







Co-Hg 











4-042 









-0-56 



Pfc,-Cu 





-0-12 







-0-06 



4-0-09 



4-0-21 







Pt 2 -Ou 





-0-13 







-011 







4-0-67 



-0-21 



Sn,-Cu 





-020 











4-0-34 



4-0-40 



4-0-30 



Mg-Cu 





+0-11 







4-0-22 



-0-37 



4-0-11 







Al-Cu 





+0-16 







4-0-18 



-0-18 



+0-15 







a. s.-cu 



... 



-001 







4-0-16 



4-011 









Average 



-0-12 



-007 







+009 



4-005 



4-0-16 



-0-12 



Phil. Mag. S. 5. Vol. 41. No. 253. June 1896. 2 L 



