A Comprehensive Treatise on Inorganic and Theoretical Chemistry

PLATINUM 119
platinum to the cold metal when in contact with antimony, arsenic, platinum,
copper, silver, lead, tin, zinc, mercury, iron, nickel, gold, and bismuth. Observations
on the subject were made by J. Gumming, W. G. Hankel, P. O. C. Vorsselmann-de-Heer,
H. Rohmann, W. Rollmann, A. Abt, J. M. Gaugain, N. F. Mott, and
A. Matthiessen. H. Ie Chatelier observed that with purified platinum, its position
in the thermoelectric scale is not altered by annealing. N. A. Hesehus studied
the subject. Observations on the sensitiveness of thermocouples were made by
K. E. F. Schmidt ; the neutral points were discussed by Lord Kelvin, P. G-. Tait,
C. G. Knott and co-workers, and M. Chassagny and H. Abraham. C. Benedicks
and C. W. Borgmann studied the influence of gas ions on the electrothermal effect ;
and A. V. Makaroff and I. V. Plastinin, the thermoelectric homogeneity of platinum
wires.
A. C. Becquerel observed a thermoelectric force with a thermocouple of
platinum wires in contact whereby a current flows from the hot to the cold wire ;
G. Magnus, A. C. Becquerel, B. Li. Rosing, J. M. Gaugain, F. C. Henrici, P. Raethjen,
and W. Durham observed a thermoelectric force with wires of different structure,
e.g. hard and soft wires. F. P. Ie Roux, and E. Cohn observed that with a stretched
and an unstretched wire, a current flows through the hot junction from the
stretched to the unstretched wire—Lord Kelvin added that this occurs only if the
stretching is permanent ; and E. Wagner found that a compressed wire gives a
thermoelectric force against an uncompressed wire, amounting at 58°, and a
press, of a kgrm. per sq. cm., to 0-010186 volt per degree. P. W. Bridgman observed
that the thermoelectric force, E X IO 6 volts, with a couple of platinum uncompressed
and compressed at p kgrms. per sq. cm. :
P 10° 20° 40° 60° 80° 100 u
{ 2,000 . 0-30 0-63 1-4O 2-23 2-98 3-60
6,000 0-91 1-96 4-28 6-61 8-76 10-70
12,0OO . 1-79 3-88 8-60 13-39 17-76 21-57
and the results with one sample of purified platinum against lead were E X10°
= —30920—00133402 volts; and with another specimen, E X10« — — 1*7880
—G-Ol 730 2 +O-O4420 a volts. K. Tsuruta studied the effect of longitudinal tension ;
G. Tammann, and G. Tammann and G. Bandel, the effect of cold work. V. B. Lewes
observed that molten platinum heated in the oxy-hydrogen flame gives a greater
thermoelectric current than does the molten metal near the m.p. C G. Knott,
and J. Monckman observed that a thermoelectric current flows through the hot
junction from non-hydrogenized to hydrogenized platinum. W. Ende, and G. Meyer
studied the effect of striction ; and J. L. Hoorweg, the effect of different kinds of
platinum. J. Wiirschmidt, and G. K. Burgess and P. 13. Sale determined the purity
of the platinum by determinations of its thermoelectric force. R. M. Holmes
measured the thermoelectric force of these couples. F. Jenkin observed a thermoelectric
current between platinum and platinum covered with copper oxide ; and
R. Bunsen, with platinum and pyrolusite, or platinum and copper pyrites.
E. Heiber measured the thermoelectric force of platinum against the solid
alkali metals—Li, Na, K, Rb, and Cs. H. C. Barker found that for a temp, difference
of 0°, the thermoelectric force, E microvolts, of the platinum-potassium couple is :
0 . 89-50° 70-86° 50-84° 40-24° 28-64° 17-70° 6-82°
E . 84O 67O 480 38O 370 170 7O microvolts
or —0*94 millivolt at 100°. Observations were also made by A. Naccari and
M. Bellati. H. C Barker gave for the platinum-sodium couple —0-21 millivolt
at 100°, or
0 . 84-24° 73-60° 63-46° 52-79° 41-51° 32-16° 12-64°
E . 170 150 13O HO 90 70 3O microvolts
A. Abt, A. C. Becquerel, J. W. Draper, E. Edlund, J. Galibourg, J. M. Gaugain,
A. Hiel, W. Jager and H. Diesselhorst, I. Klemencic and P. Czermac, G. G. de Metz,