( 210%) 
EINSTEIN). A priori, it seems to be not impossible that @ increases 
over a definite temperature region as the temperature rises. 
In the meantime all these theories do no more than emphasise 
the fact that the behaviour of helium forces us to question the sig- 
nificance of the absolute zero with respect to molecular attraction. 
Hence it is of first consequence to obtain data concerning the ther- 
mal properties here mentioned in connection with helium that 
would lead to the solution of these problems, and also to investigate 
related properties such as capillarity, viscosity, specific heat, refrac- 
tive index and dielectric constant, for which data are still lacking. 
For this purpose the solution of the problem of transferring liquid 
helium to a vessel in which the regenerator spiral no longer inter- 
feres with the introduction of measuring apparatus is absolutely 
essential. 
B. On the change in the resistance of pure metals at very 
low temperatures, ete. 
LIL. The resistance of platinum at helium temperatures. 
§ 1. The resistance of a wire of very pure platinum at helium 
temperatures. As soon as the possibility had been attained, it lay at 
hand to extend to helium temperatures the investigation of the change 
of electrical resistance of pure metals which, in Comm. N°. 99e (Sept. 
1907), had been brought down to the lowest hydrogen temperatures. 
For this purpose the resistance (tg which had been calibrated at 
hydrogen temperatures as well as at others with the resistance 
Pty of Comm. N°. 995 (Sept. 1907) was available. It was constructed 
on the model of Pf, (Comm. No. 995 § 2), and is indicated by 2 
on Plate I of part 4: of the present paper, tig. 1. The thin platinum 
wire is wound round a glass cylinder and is kept tight on it by 
being wound while hot, and the thicker platinum ends JI’, and I, 
are fused to the giass. To these ends the double platinum leads 
Wa, Wa, and W,,, Wy, are attached; they are not, however, 
welded in the blowpipe, but are simply tin-soldered. The resistance 
was measured on the Weartstone bridge according to the method 
described in Comm. No. 99 and previous Communications. The ratios 
of w,, the resistance at the temperature of the observation, to w 
that at 0° C., are here given (p. 1108). 
From this it appears that by descending to helium temperatures 
the resistance is still further diminished, but when these temperatures 
are reached the resistance attains a constant value quite independent 
of the individual temperature to which it has been brought. The 
0° 
