i ! PYRO-ELECTRIC PROPERTIES OF ALLOYS. 157 
Other relevant results.— A research into the relations of electrical con- 
ctivity and temperature makes up an important part of the labors of 
itthiessen. In addition to his well-known results for pure metals, 
itthiessen 1 and his friends investigate the electrics of alloys Pb, Sn 
1, SnCu, SnAg, ZnCu, AuCu, AuAg, PtAg, PdAg, CuAg, FeAu, Fe- 
i, PCu, AsCu, and some other metals. Unfortunately, not all of these 
oys are available for the present discussion, for Matthiessen's purpose 
ems rather to have been the exploitation of a great number of series 
groups of alloys. On the other hand, it is my purpose to examine 
e electrical behavior of as many alloys as possible of a single given 
oup. In Matthiessen's work the three PbAg alloys and the two SnAg 
ioys lie too far apart. 
On perusing Matthiessen's andVogt's results it appears that Pb alloys, 2 
i alloys, and Fe alloys will have to be excluded from the present con- 
leration, inasmuch as the data are either insufficient in number or lie 
far apart from each other and from the extremes of the series, or be- 
use of mechanical difficulties encountered in making the alloys and 
aping the wires. Perhaps there are other reasons. There remain a 
ry full series of copper alloys, namely, CuSn, CuZn, CuFe, CuP, 
lAs, a series of silver alloys, viz, AgAu, AgPt, AgPd, AgCu ; and a 
w gold alloys, viz, AuGu, AuAg. 
In view of the importance of these data I have computed the fallow- 
s' tabular statement of Matthiessen's results, re-arranging the data in 
ivay which, for my special purposes, is expedient; and I have also 
ded Matthiessen's 3 results for pure metals. In Table 40& \' Q denotes 
b conductivity in Matthiessen's standards (Ag=100), a the tempera- 
re-coefficient of the alloy of which the composition is given on the 
me horizontal row. I have rounded off Matthiessen's large numbers, 
cause the arbitrary errors introduced during the mechanical prepara- 
>u of the alloys, together witli the errors of structure and hardness 
d the more serious errors of imperfect homogeneity make the extreme 
curacy of the electrical datum illusory. The table furthermore con- 
ins A , the electrical conductivity in microhms referred to the cubic 
atimeter. This reduction is made by means of mercury. 4 In the 
5t two columns of Table 40a the value of a, computed by the formula 
\-m=n\ and the corresponding errors are inserted. Of these re- 
sults further mention will be made below, and I need here state only 
at the constants m and n, given at the end of the table, were derived 
>m all the observations by the method of least squares. The com- 
Matthiessen and Vogt : Pogg. Ana., vol. 12, 1864, p. 19. 
The metallic ingredient present in the alloy in larger amount is fitly used in desig- 
ning the alloy. 
Matthiessen u. v. Bose: Pogg. Ann., vol. 115, 1862, p. 353. 
Jenkin, who made similar reductions in the case of pure metals by means of 
d, arrives at somewhat different numbers. A satisfactory absolute table can not 
constructed. 
(811) 
