STRUCTURE OF TUNGSTEN WIRES 
97 
far as the present tests are concerned. The photographs show that 
the crystal structure near the surface is distinctly different from 
that throughout the body of the crystal. Tn No. 1 the lighter-col- 
ored rim, free from crystals (or apparently so) is clearly in evi- 
dence. In No. 2 the same ring appears, and it is practically of the 
same depth as that in No. 1. In No. 3 the light area has pene- 
trated much farther, the dense crystals being very much less in 
evidence. In No. 4 the dark crystals are to be seen only in isolated 
spots, while in No. 5 the dark grains are totally absent. This ef- 
fect can not be attributed to variations in polishing and in etching, 
for throughout the wires were treated exactly alike in order to 
avoid that contingency. 
Exactly what the difference is between the two phases of crys- 
tal structure, the writer is not in a position to state. He is of the 
opinion, however, that the light-colored areas represent the fact 
that the amorphous cement is much in excess, and that the crystals 
in that region are so fine as to be beyond the resolving power of 
the microscope. According to modern theories of such crystals, 
the amorphous state should exhibit the higher elasticity. 
In conclusion, whatever the structures of the two crystal states 
may be, it has been demonstrated that drawing has an effect on the 
surface which is different from the effect deeper in the structure 
of the wires. This accounts for the progressive changes in the 
elastic constants of the wires. 
State University oe Iowa. 
