Vol. 8, 1922 
PHYSICS: J. A. ANDERSON 
231 
1909 (465-473), also Congress Geologigues International, ii Session, Stockholm^ 
1910, 1, 1912 (203-211). 
14 Schreiber, H. Nacheiszeitliche Klimaanderung und Moorbildung in Skandinavien. 
Oesterreicshische Moorzeitschrift, 15, 1914 (104). 
15 Wahnschaffe, -F. tiber die Gliederung der Glazialbidungen Norddeutschlands 
und die Stellung des norddeutschen Randlosses. Zs. Gletscherk, 5, 1911 (321-338). 
16 Weber, C. Z. Was lehrt der Aufbau der Moore Norddeutschlands iiber den Wechsel 
des Klimas in post glacialer Zeit? Zs. Deut. Geol. Gesell., 62, 1910 (143-162). 
THE SPECTRAL ENERGY DISTRIBUTION AND OPACITY OF 
WIRE EXPLOSION VAPORS 
By J. A. Anderson 
Mount Wii^son Observatory, Carnegie Institution of Washington 
Communicated, May 22, 1922 
It has been shown^ that a fine wire, through which is passed the discharge 
of a large high voltage condenser, vaporizes so rapidly that the phenomenon 
is best described as an explosion. The actual time required for the wire 
to pass from the solid to the vapor state is probably less than one millionth 
of a second. If the explosion is made to take place in the space between 
two parallel planes from 2 to 3 millimeters apart, such as a slot in a block 
of wood, its spectrum is continuous, the lines of the metal exploded appear- 
ing as absorption lines. The maximum intensity of the light is very great, 
being of the order of that to be expected from a black body at a temperature 
of about 20,000° K. 
A preliminary study of the spectral energy distribution given by the 
explosion of iron wires has been made, using a quartz spectrograph with a 
vacuum thermo-couple^ and galvanometer. The value of E\d\ increases 
very rapidly from the infra red to about X4300; from this point to the ultra 
violet the great groups of iron absorption lines cause the values of E\d\ 
to oscillate considerably but its general tendency is upwards and the highest 
values are reached between X2600 and X2150. From X2150 to X1990 the 
values fall off rapidly, in part, perhaps, due to the absorption of the quartz 
lenses and prisms, and to that of the air. 
Spectrograms of the explosions of the following metals have been made 
using a one meter focus grating spectrograph : copper, silver, gold, magne- 
sium, zinc, cadmium, aluminum, tin, lead, tungsten, iron and nickel. All 
of these give continuous spectra of the same general intensity most of them 
appearing rather more intense than iron on account of the numerous ab- 
sorption lines of the latter. Copper, silver and gold are anomalous in that 
the pure wires of these metals will not explode properly when placed in a 
slot in a block of wood, the main discharge always seeking a path around the 
