150 



A. L. Day and R. B. Sosman- 



The untrustworthiness of the present practice of extending 

 thermoelement values obtained below 1100° into the region 

 above that temperature is therefore abundantly demonstrated.'* 



We were unable to lind a simple parabola with which to 

 represent the whole series of observations between 300° and 

 1550° within the errors of observation. The simplest proce- 

 dure is therefore to divide the long curve into two parts. This 

 plan is carried out below in the form in which it will probably 

 be found most useful. A parabola passing through zinc, anti- 

 mony and copper reproduces the results over that temperature 

 range within the errors of observation. A similar parabola 

 through copper, diopside and palladium gives the upper tem- 

 peratures as accurately as they were measured. These two 

 equations offer a means of safe and convenient interpolation 

 throughout the entire range of the gas thermometer measure- 

 ments. In this series are included certain gas thermometer 

 measurements given at the end of Table YIII which were 

 made at temperatures between the lixed melting points, for 

 the purpose of checking the interpolation formula, together 

 with a single gas thermometer determination of the cadmium 

 melting point. The temperature 854*1 appears here corrected 

 by —0*6°, since the series, of which this measurement formed 

 a part, showed a systematic difference of about this amount 

 from the final average of antimony and silver, which lie on 

 either side of this point. 



Cadmium to Copper 



E= —302 4- 8-2356-J + '0016393* 2 



Observed— 



Observed Calculated Calculated 



Temperature Microvolts Microvolts Microvolts 



Cadmium 320-0° 2504 2501 +3 



Zinc 418-2 ■ 3429 3429 



524-9 4470 4472 —2 



Antimony 629'2 5530 5530 



854-1 7927 7928 —1 



Silver 960-0 9113 9115 —2 



Gold .... 1062-4 10295 10298 —3 



Copper 1082-6 10534 10534 



Copper to Palladium 

 E = — 1941 + 11-1746£ + '00032161£ 2 



Copper 1082-6 10534 10534 



1207-1 12000 12010 —10 



1298-8 13100 13112 —12 



Diopside 1391-2 14228 14228 



Nickel 1452-3 14977 14967 +10 



Cobalt 1489-8 15439 15421 +18 



Palladium 1549-2 16143 16143 



* For an account of some of the dangers of careless interpolation, see Day 

 and Clement, loc. cit., p. 453. 



