Thermoelectrics of Platinum-irldium <§'C. 



377 



the platinum-indium observations were made, could be taken 

 with an accuracy of O'l per cent. 



The table therefore contains the electromotive forces, in 

 microvolts, of iridioplatinum-platinum, e, and rhodioplatinum- 

 platinum, e', at the times specified and for the temperatures, 

 tj of the cold junctions, when the hot junctions are identically 

 heated. It also contains the electromotive forces e 2 o an d ^'20* 

 for the case where both cold junctions are at 20° C, as well 

 as the ratio, ^'20/^20? of the two. 

 Table I. — Comparison of the thermoelectrics of the platinum- 



iridium (20 per cent.) and the platinum-rhodium (10 



per cent.) thermocouples. Flame off. 



Time. 



t. 



Pt-Ir. 



e. 



Pt-Rh. 



e'. 



e 20 . 



e 20 . 



I0 3 xe' 20 /e 20 . 



m. 



°C. 



microvolt. 



microvolt. 



microvolt. 



microvolt. 





57 



290 



21863 





21930 



* 





59 



290 





15410 









61 



291 



18118 





18190 



14020 



771 



63 



291 





12767 









65 



292 



15343 





15410 



11790 



765 



67 



292 





10877 









69 



293 



13308 





10380 



10210 



764 



71 



293 





9574 









73 



294 



11852 





11920 



9070 



761 



75 



29-4 





8521 









77 



295 



10595 





10670 



8110 



760 



79 



295 





7640 









81 



295 



9517 





9590 



7310 



762 



83 



29 5 





6882 









85 



295 



8575 





8650 



6590 



762 



87 



29-5 





6217 









89 



295 



7770 





7845 



5980 



763 



91 



29-5 





5631 









93 



29-6 



7044 





7120 



5410 



760 



95 



296 





5109 









97 



296 



6391 





6470 



4920 



761 



99 



29-6 





4653 









101 



29-7 



5822 





5900 



4500 



764 



103 



297 





4251 









105 



297 



5315 





5390 



4120 



764 



107 



29-7 





3874 









109 



29-8 



4870 





4950 



3770 



763 



111 



29-8 





3552 









113 



298 



4466 





4540 



3460 



763 



115 



298 





3255 









117 



29-9 



4082 





4160 



3170 



763 



119 



299 





2963 









121 



29-9 



3740 





3820 



2910 



760 



123 



29-9 





2721 









125 



300 



3428 





3510 



2670 



762 



127 



30-0 





2502 









129 



30-0 



3145 





3220 



2460 



764 



131 



300 





2301 









133 



300 



2880 



... 



2958 



2281 



771 



135 



300 





2122 









* Cooling too rapid for interpolation. 



