1888.] Prof. Tait on ThermoeUctric Properties of Iron. 129 
“ The PeCu deflections were now plotted against the PdCo deflec- 
tions, and the constants of the curve calculated, points being verified 
as before. 
“ The experiments on ‘Battelli’s iron’ were carried out in the same 
way. The two FeCu curves were then compared, with the follow- 
ing results. 
“ Eatio of distance between origin and neutral point, to distance 
between neutral and vanishing points 
“ If we assume the specific heat in iron to be expressed by k-f -t- W, 
while that in copper is we find from the curves that \ and I are 
both negative \ and we have 
In this paper the author pointed out that the experiments detailed 
in his preceding paper on Transition-resistance and Polarisation, 
show that, whatever be the ultimate nature of Dielectrics, any 
insulator upon which a film of gas is condensed must exhibit the 
phenomena of electric absorption and residual discharge. 
7. On Mr Omond’s Observations of Fog-Bows. 
The author remarked that one of the constituents of the double 
fog-bow described in some of Mr Omond’s recent observations, is 
obviously the ordinary primary rainbow, diminished in consequence 
of the very small size of the water drops. But the other, having 
nearly the same radius but with its colours in the opposite order, 
appears to be due to ice-crystals in the fog. This is quite con- 
VOL, XV. 21/6/88 I 
I Ordinary Iron, 
Observed 1 ; 075 
Battelli’s Iron. 
1:079 
iron 0-0011 
„ 0 - 0021 .” 
0. On the Constitution of Dielectrics. 
By W. Peddie, B.Sc. 
{Abstract.) 
By Prof, Tait. 
