Copper, Aluminum, and Lead. 283 
is the “Lost Motion’. When a wire is stretched the crystals break down and 
are drawn out in the direction of the length of the wire. The amorphous 
phase that is produced in the breakdown fills up such crevices as may be 
created due to the displacement and breaking up of the crystals. When 
the stress is removed such crystals as remain intact cannot return to their 
original position because of the presence of the amorphous phase. The 
broken crystals have lost much of their elastic property. Both of these 
causes tend to produce a permanent set or permanent elongation in the 
specimen. 
Acknowledgement is made to Prof. Lemon of Ryerson Physical Laboratory 
for his suggestions and help on this problem. I am also indebted to the 
Physics Department of Chicago University which provided the equipment 
necessary. 
Bibliography. 
1. E. N. da ©. Andrade, The Flow in Metals Under Large Constant 
Stresses. Proc. Roy. Soe. Vol. 90, page 329, 1914. Also Vol. 84 of the 
same publication. 
2.- G. Quincke, Die Schaumstruktur der Metalle, Internat. Zeitach. f. 
Metallographie ITI, 1 page 23, 1912. 
3. J. A. Ewing and Walter Rosenhain, The Crystalline Structure of Metals. 
Proce. Roy. Soc. Vol. 67 page 113, 1900. 
4, G. T. Beilby, The Hard and Soft States in Ductile Metals,—Proc. Roy. 
Soe. Vol. 79, page 4638, 1907. 
5. <A. A. Michelson, Behavior of Substances Under: Torsion.—Proc. Nat'l 
Acad. Se. 1917. 
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