( 345 ) 



The third column contains 1 lie determinations aboui the element 

 constantin-steel of Table VI in Comm. N°. 1)5" (Sept. '06). Owing 

 to (lie great lessening of the increase of the electromotive force per 

 degree this element is unfit for the accurate measurement of the 

 lowest temperatures l ). 



We shall soon publish a calibration of the thermo-element gold- 

 silver with the helium thermometer at low temperatures. 



Physics. "()n the change of the resistance of pure metals at very 

 loir temperatures and the influence exerted on it Ay small 

 amounts of admixtures. II. By 11. Kamerlingh Onnes ami 

 .1. ('lav. Communication N°. 107' from the physical laboratory 



at Leiden. 



(Communicated in the meeting of May 30, 1908). 



§ 7. Supplementary notes lo Comm. X". 99 c (Sept. '07). We add 

 to it with regard to 2 ) : 



Gold. A formula of I lie form I) has been derived lor Auy. The 

 drawing thinner of gold wire has the same influence as we remarked 

 in the comparison of the thin wire Ptd with Ptj in Comm. X". 99 /j 

 (Sept. '07) which influence was ascribed to impurities. With two 

 gold wires it was possible bv means of analysis to show the difference 

 in composition called forth bv drawing. 



Mercury. The values given in Comm. N°. 99 are represented 

 (except at 0°) by the quadratic formula. 



W t — 22 . 3605 (1 -f 0.00358 / - 0.06588 f 1 ) 

 which tor -J97°.87 gives — C =-{- 0.0106 so that we are 

 led to think that the temperature has not been observed quite accurately 

 enough. Of the metals investigated it seems that mercury is best 

 suited for the measurement of temperatures below the meltingpoint 

 of hydrogen. 



Lead. For lead two formulae were derived of the form A' and B' 



A and B each time with omission of the term r ( I ), according 



') Also the element german silver-platinum investigated by Dewab (Proc. Roy. 

 tSoc. ser. A, vol. 76 p. 316 sqq. 1905) is unfit for this purpose because of the 



same fault. 



-) Observations, formulae ami oilier details arc given in ,1. Clay's thesis for 

 the doctorate, and in Comm. N°. 107c lor the sections 7 and S, in Comm. 

 N'. 1U7</ for § '.». 



23* 



