Intelligence and Miscellaneous Articles. 77 



When the light of an indium-flame is decomposed by the prism, it 

 shows two blue lines, one of which, very intense, is situated close to the 

 blue strontium-line, but a little further towards the violet end of 

 the spectrum ; the other line is still more refrangible, but so much 

 fainter that it cannot be perceived at all in the spectrum produced 

 by means of a grating. — Poggendorff's Annalen, vol. cxxiv. p. 637 

 (1865, No. 4). Communicated by the Author from the Berichte 

 iiber die Verhandlungen der Gesellschaft zur Beforderung der Natur- 

 wissenschaften zu Freiburg in Breisgau. 



ON SOME THERMO-ELEMENTS OF GREAT ELECTROMOTIVE FORCE. 

 BY. J. STEFAN. 



In investigating the thermo-piles constructed by Marcus, some 

 minerals which were just at hand were investigated as to their thermo- 

 electric deportment at high temperatures. The method was as fol- 

 lows : — The mineral to be investigated was laid upon one end of a 

 copper strip, the end of a wire laid on the mineral, and the whole 

 pressed by means of a clamp. This wire, and one from the free end of 

 the copper strip, lead to a galvanometer with great resistance. The 

 copper strip is heated by a spirit-lamp flame. In order to join any 

 two minerals to a thermo-element, a copper strip was laid between 

 them, wires laid on their most distant sides, and the whole pressed 

 by a wooden clamp. The free end of the copper strip was introduced 

 into the flame, and served therefore only as conductor of heat to the 

 place of contact. 



In the following recapitulation of the elements, the electropositive 

 body is always placed first. The number given signifies how many 

 of the elements joined together furnish an electromotive force equal 

 to that of a Daniell's element. 



1. Foliated copper pyrites . Copper 26 



2. Compact copper pyrites Copper 9 



3. Pyrolusite Copper 13 



4. Compact copper pyrites . Foliated copper pyrites ... 14 



5. Copper Crystallized cobalt pyrites . 26 



6. Granular cobalt pyrites . Copper 78 



7. Copper Iron pyrites 15*7 



8. Compact copper pyrites. ,, 6 



9. Foliated copper pyrites . ,, 9 "8 



10. Copper Variegated copper ore .... 14 



11. Fine Bleischweif Copper 9"8 



12. Coarse Bleischweif .... Copper 9 



13. Galena in large crystals. Copper 9'8 



14. Bleischweif Variegated copper ore .... 5*5 



Copper pyrites and pyrolusite have been already investigated by 

 Bunsen*. His experiments, made with picked specimens, give num- 



* Phil. Mag. S. 4. vol. xxix. p. 159. PoggendoriF's^mia?e?i, vol. cxxiii. 

 p. 505. 



