216 IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
SET III. 
Pb. 
1.96 
glass 
2.40 ; 
Kj 
/K g = 
14.2 
Te. 
2.24 
glass 
2.40 ; 
K t 
/K g = 
1.39 
K x /K t = 
= 14.2 / 1. 
39 : 
= 10.2 
SET IV. 
Pb. 
2.47 
glass 
4.84 ; 
Kx 
/Kg £» 
14.5 
Te. 
2.24 
glass 
4.54 ; 
K t 
/Kg = 
1.33 
Kx/Kt = 
14.5 / 1.38 
= 10.9 
Reducing the ratio K sn /Kt to terms of lead by multiplying 
by the fraction .082/.150 (the conductivities of lead and tin at 
the temperature of experiment) gives K\/K t ~=8.9. The average 
of these four values gives Kj/Kt— 9.6. 
The greatest variation from this average is 13.5 per cent. At 
the temperature of the experiment (25 to 35 degrees C.) the 
value of K t is . 082/9. 6=.0085. 
The value as given by Wold 9 and King 10 is .0135. There is 
thus a difference of 59 per cent between the two values. How- 
ever, this is not at all surprising with the poorer conductors. 
Ingersoll and Zobel * 11 make this statement in regard to them: 
“ While the values of K for the metals are probably correct to 
about 1 per cent, no such accuracy can be claimed for the poorer 
conductors, as the disagreement between different observers is 
frequently 50 per cent or even more.” It should be particularly 
noted, also, that the method used by the author was designed pri- 
marily for the poorer conductors while that of Wold 12 and 
King 13 is best suited to the better conductors. 
The Physical Laboratory, 
The State University. 
9 Loc. cit. 
10 Loc. cit. 
11 Math. Theory of Heat Conduction, p. 161. 
12 Loc. cit. 
13 Loc. cit. 
