358 C. A. Young—Thermo-electric power of Iron, etc., in vacuo. 
mit. H 
notable elevation, though the companion of H was visible at the 
base of the prominence. The H- and K-lines also showed evidence 
of violent cyclonic action, just as id. / was only faintly visi- 
e in the prominence; F a he line near Y were of course 
strong. But no other lines, either of sodium, magnesium, or 
anything else, could be traced more than a very few seconds of 
are above the sun’s limb. I am not able to say how long the H- 
lines continued visible, or to what elevation they extended after- 
wards, as I returned to the C-line to watch the termination of the 
eruption. If I remember rightly, this eruption reached a higher 
elevation than any before observed. ere was (and is to-day) 
nothing on the sun’s limb visible with the telescope which would 
account for it. 
Princeton, Oct. 8. 
ArT. XXXVIII.— On the thermo-electric power of Iron and 
Sarina im vacuo; by Professor C. A. YounG, of Princeton, 
EXNER, a few months ago, published a paper asserting that 
the thermo-electric power of antimony and bismuth is de- 
stroyed by removing them from all contact with oxygen, and 
immersing them in an atmosphere of pure nitrogen. From 
this he argues that the thermo-electric force in general is due 
to the contact of the gases which bathe the metals. The 
following experiment was tried to test the theory : 
y the kindness of Mr. Edison and Mr. Upton a vacuum 
tube was prepared in Mr. Edison’s laboratory, containing an 
iron wire, about two inches long, firmly joined to two platinum 
terminals which passed through the walls of the tube; the 
tube was exhausted until the spark from a two-inch induction 
coil would not pass ¢ of an inch in the gauge-tube, indicating a 
The wi 
reflecting galvanometer was included in the circuit. By laying 
the tube and connected joinings in the sunshine, and alter- 
nately shading one or several of the joinings it was found that 
the electro-motive power of the joinings within the tube was 
precisely the same as that of those without, and the develop- 
ment of current just as rapid. There was no trace of any 
modification due to the exhaustion. 
