LIBERATION OF ELECTRONS 
307 
THE ABSENCE OP LIBERATION OR ABSORPTION OP 
ELECTRONS DURING A CHANCE PROM THE CON- 
DUCTING TO THE NON-CONDUCTING STATE. 
L. E DODD. 
Metallic selenium in the crystalline form is an electrical con- 
ductor. In the amorphous form, which may he produced by 
melting a selenium crystal, the substance is an electrical insula- 
tor. If, as supposed, electrical conductivity in metals is due 
to free electrons, then in the change from the conducting to the 
non-conducting state there must be a disappearance of free elec- 
trons. This disappearance could be accounted for by a libera- 
tion of electrons into the space surrounding the substance, or by 
a recombination of free electrons with positive residues to form 
the neutral molecules of the insulator. In this paper is described 
an experiment to test the question of liberation of electrons dur- 
ing a change from the conducting to the non-conducting state. 
E 
Fig. 15. — Diagram showing melting of selenium crystals. 
