The order of the metals, beginning with that which becomes negative with all others, is, 1. Bismuth.
2. Nickel.
3. Cobalt.
4. Palladium.
5. Platinum. Several pieces of this metal gave very different results, even those which came from the same work shop. Three pieces from Jean netty's platina manufacture were placed in the order of their effects very far from each other. The pieces which kept this place here between palladium and uranium were prepared by Dr. Wollaston, Mr. Bergemann, chemist at Ber lin, Mr. Trick, chemist, appoint ed to the manufacture of china at Berlin, and Mr. Jeannetty at Pa ris. As one of these pieces was prepared by Dr. Wollaston, and the two Berlin chemists being men of much chemical skill, we may consider this place as that of the pure platinum, if Mr. Becquerel had not found that two parts of the same platinum wire give a con siderable thermoelectric action, when one of them was drawn out so as to become much thinner. Hence it appears that the density of the platinum has a considerable influence upon its thermoelectri cal effect. This might perhaps also be the case with other metals.
6. Uranium.
7. Copper, reduced from the oxide by means of black flux, Comp. No. 12.
8. Manganum.
9. Titanium.
10. Brass, some specimens. (Comp. No. 13.) 11. Gold, of Hungarian ducat containing alloy of silver and copper.
12. Copper, occurring in the trade, and taining no silver, iron, lead, or sulphur. (Comp. 21.) 13. Brass, some specimens. (Comp. No. 10.) 14. Platinum, a piece of unknown origin. (Comp. No. 5, 18, 29.) 15. Mercury, the purest occurring in trade.
16. Lead, specimens occurring ill trade, and pure lead.
17. Tin, English and Bohemian.
18. Platinum, A bar from Jeannetty's manufac ture.
19. Chromium.
20. Molybdxnum.
21. Copper, occurring in trade, and containing neither silver, iron, lead or sub phur. (Comp. 12.) 22. Rhodium.
23. Iridium.
24. Gold, a, purified by antimonium, b, duced from the oxide.
25. Silver, a, purified by cupellation, b, duced from the chloride of silver.
26. Zinc, a, occurring in trade, b, pure zinc.
27. Copper, reduced from sulphate of copper, a, by iron, b, by zinc. (Comp. 12. and 21.) 28. Wolfram.
29. Platina, some specimens, (Comp. 5, 14,18.) 30. Cadmium.
31. Steel.
32. Iron, a, occurring in trade, b, pure iron.
33. Arsenic.
34. Antimony, a, occurring in trade, b, pure.
35. Tellurium.
In this series, Dr. Seebeck found that though most of the metals placed here near each other give only a feeble effect, and the more distant a stronger effect, this rule is not constant; tellurium, for in stance, gives with bismuth less effect than anti mony. With most of the metals in the series tel
lurium produces a feebler effect than antimony; with silver it produces more effect than with most of the metals placed above it. Antimony produces more effect with cadmium than with mercury. Iron pro duces only a feeble effect with most of the other metals, and particularly with nickel and cobalt. Of such exceptions Dr. Seebeck has found a great many.
Dr. Seebeck also examined the thermo-electrical powers of several other bodies. Sulphuret of lead becomes negative even in contact with bismuth. Some other sulphurets, as sulphuret of iron, of arsenic, of cobalt and arsenic, of copper, all with a maximum of sulphur, stand in the thermo-electri cal series very near to the bismuth. On the con trary, the sulphurets with a minimum of sulphur stand very near to antimony; that of copper stands even under antimony.
Dr. Seebeck found also that concentrated nitric and sulphuric acids arc to be placed above the bismuth, but that a concentrated solution of potash or of soda, obtains a place below antimony and tellurium.
Dr. Seebeck constructed also circuits of two pieces of one metal; heating or melting one of the pieces, and putting one extremity of the other piece, which must be bent, in durable contact, while the opposite extremity was in temporary con tact with the heated piece. A bent silver wire was, for instance, plunged first with one of its ex tremities and afterwards with the other in melted silver; the magnetic needle indicated that the cur rent was directed from the melted metal to that ex tremity which had been the longest time in contact. The same effect, though feebler, was observed when the silver had ceased to be liquid. When a platina wire is tried with a heated piece of platina the di rection of the current is opposite. The general re sult of Seebeck's experiments is, that in the metals of the superior part of the thermo-electric series the direction of the current is as in the platina going from the heated metal to that extremity of the bent piece, which is latest put in contact with it; but in the inferior part of this series the current goes, as in the silver, from the heated metal to that extre mity of the other metal, which has been longer in contact with it.