



én Alloys of Bismuth and Tin. 577 
X. Summary of Results. 
We are now in a position to infer the manner of the 
variation of the magnitude of the specific heat of electricity 
with composition in the case of these alloys. 
From fig. 6, which represents the relation between o and 
percentage of tin, we see the striking effect of the addition 
of a very small amount of tin to bismuth, the Thomson effect 
in an alloy containing 1 per cent. tin being more than 
12 times as large as in pure bismuth. 
With the addition of more tin, the value of the Thomson 
effect continues to increase until the alloy contains about 
3 per cent. tin, when the effect is about 15 times as large as. 
for bismuth. When the percentage of tin is increased 
Fig. 6. 

pi rst-fleoh AGH PERCENTAGE 
10 20 30 40 50 
beyond this amount, the value of the specific heat of electricity 
begins to decrease : this diminution goes on as the amount 
of tin becomes greater, until finally the Thomson effect in 
the case of pure tin has fallen to a value which is only about 
3% part of that which holds in the case of bismuth. 
It may, indeed, happen that traces of substances other 
than tin in bismuth produce a considerable change in the 
value of the Thomson effect, and any discrepancies between 
the values obtained for different specimens of bismuth may 
well be attributed to the presence of such impurities (see 
. 570). 
. [These experiments also indicate that in the case of alloys 
at any rate the specific heat of electricity is not necessarily 
proportional to the absolute temperature. A similar result 
has been previously pointed out by Haga, whose experiments 
Phil. Mag. 8. 6. Vol. 7. No. 41. May 1904. 2R 
0 
