CO.MPAKISON OF PLATINUM AND GAS TIIKI;M< >\IK IKlCS. 



CALLENDAR employs the symbol pt, its value deluding on the sample of platinum 

 chosen. 



In order to reduce to the standard scale of temperature the indications of any 

 platinum thermometer, it is necessary to know the law connecting T and pt. These 

 are, of course, identical at and 100, but the determination of the remainder of the 

 curve expressing the relationship between them is a matter for experiment. Our 

 present knowledge of this relation depends mainly on the investigations of CALLENDAR 

 and GRIFFITHS. 



The following is a list of the principal papers published bearing on the subject of 

 platinum thermometry : 



CALLENDAR ..... . . 'PhiL Trans.,' A, 1887. 



. ...... ' Phil. Mag.,' July, 1891. 



July, 1892. 



....... February, 1899. 



GRIFFITHS ........ 'Brit. Assn. Reports,' 1890. 



.......... 'PhiL Trans.,' A, 1891. 



.' : . . . .'"'". . . 1893. 



......... 'Proc. Roy. Soc.,' vol. 55, 1894. 



........ 'Nature,' November, 1895. 



. ..... '. . February, 1896. 



CALLENDAR and GRIFFITHS . . ' Phil. Trans.,' A, 1891. 



CAREY FOSTER ...... ' Nature,' August, 1894. 



HEYCOCK and NEVILLE . . . 'Chem. Soc. Journ.,' 1890. 



... ,, 1895. 



GRIFFITHS and CLARK . . . . 'Phil. Mag.,' December, 1892. 



CLARK ......... ' Electrician,' vol. 38. 



OLSZEWSKI ........ 'Phil. Mag.,' August, 1895. 



DEWAR and FLEMING .... September, 1 893. 



July, 1895. 



HAMILTON DICKSON ..... December, 1897. 



..... June, 1898. 



D. K. MORRIS ....... September, 1897. 



WAIDNER and MALLORY . . j : August, 1897. 



DAY ...... .... August, 1897. 



CHREE ......... ' Nature,' July, 1898. 



The work of CALLENDAR established for a particular sample of pure platinum the 

 relation 



over the range O c to 600. For CALLENDAR'S wire the value of 8 was about 1 '57. 

 Subsequent experiments by CALLENDAK and GRIFFITHS showed that the values 



