( 1705-4 
Resistance of platinum wire Pt! 
7 Wi 
Wo 
273-09 K | 
ee), 0.0171 
14 0.0135 
4.3 0.0119 
9.3 0.0149 
4 35} O.O119 
results are plotted in fig. 3 PL HE, which shows well the asvmptotical 
approach of the resistance to a constant value at 4°.3 K. 
$ De The probable resistance of pure platinum and of pure gold 
at helium temperatures. In order to establish the exact significance 
of the result just obtained we must take account of the fact that 
the wire Ptp was not made from quite pure metal, and we must 
allow for the probable influence of this difference from pure platinum, 
With this end in view, we shall first confine our attention to the 
observations that have been made previously upon gold (Comm. N°. 99). 
Remembering the close resemblance between the differences of the 
resistances of platinum and of gold wires from a linear function of the 
temperature, we may, in view of the result that has been obtained with 
platinum, extrapolate the Awy resistance curve to give a constant value 
at helium temperatures. This has been done in fig. 3 of Plate III. The 
paris of the curves obtained from observations are drawn with thicker 
lines. We now note that, according to §1 of Comm. N°. 99e by 
KAMERLINGH Onnes and Cray (Sept. 1907) the influence of admixtures 
can be represented with rough approximation even down to hydrogen 
temperatures by an additive resistance that is independent of the 
temperature. In this way the line correspondingly marked in the 
figure was obtained for Aujy Which was constructed of gold of a 
smaller degree of purity (0.015°/, admixture against 0.005°/, for Avy). 
According, now, to § 1 of Comm. N°. 99c the effect of admixture 
should be pretty weil proportional to the quantity present, and this 
would lead to negative values for pure gold. In the first place, 
however, we do not know if the impurity was the same in the 
two cases, nor do we know the influence of possible tensions in the 
