A. Schrauf and E. S. Dana-~Thermo-electrical, etc. 255 
ness” referred to does not exist. Thus, in the case of the jifth 
(884—256 ; difference=128), the blending would have been 
reached, according to our law, by fifty-six beats per second. 
Art. XXII.—On. the Thermo-electrical Properties of some Minerals 
and their varieties ;* by A. ScHRAUF and Epwarp S. Dawa. 
1. All previously published investigations in thermo-elec- 
tricity have led to this result: that certain minerals are in 
part positive, and in part negative, in contact with copper, and 
that on this account, they hold different positions in the 
thermo-electrical series. 
If, for example, in the series given by Seebeck,t we number 
bismuth 1 and tellurium 34, we ha 
No. 5 Platinum (pure). | No. 7 Copper (pure, from CuO), 
Noo: & a No, 18S (commercial). 
No.8 ¢ (he “Nea 
These variations recall to mind the property which belongs to 
all metals, of suffering very great changes in cohesion, elasticity, 
etc., in consequence of a minute admixture of some foreign sub- 
stances, 
i vol. 
*From the Transactions of the Royal Academy of Sciences at Vienna, 
lxix, March 1874. Translated by E. S. Dana, and read before the American As- 
Sociation at the Hartford meeting. — 
+Seebeck, Gilb. Ann., vol. Ixxiii, 430; Pogg. Ann., vol. vi. 
