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| >> GLOSSARY OF TERMS |
| X-RAYS Light rays, excited usually by the impact of cathode rays on matter, which have wave lengths between about 10-6 cm, and 10-9 cm; also written X-rays, same as Roentgen rays. |
| YIELD POINT The load per unit of original cross section at which, in soft steel, a marked increase in deformation occurs without increase in load. |
| YOUNG?S MODULUS The coefficient of elasticity of stretching. For a stretched wire, Young?s Modulus is the ratio of stretching force per unit cross-sectional area to the elongation per unit length. The values of Young?s Modulus for metals are of the order 1012 dynes per square cm. (See Modulus of Elasticity.) |
| ZINC (Chemical Symbol Zn) - Element No. 30 of the periodic system; atomic weight 65.38. Blue-white metal; when pure, malleable and ductile even at ordinary temperatures; melting point 7870?F., boiling point 16650?F., specific gravity 7.14. Can be electrodeposited; it is extensively used as a coating for steel (See Galvanizing) and sheet zinc finds many outlets, such as dry batteries, etc. Zinc-base alloys are of great importance in die casting. Its most important alloy is brass. |
| ZIRCONIUM (Chemical Symbol Zr.) - Element No. 40 of the periodic system. Atomic weight 91.22. Specific gravity 6.5 and melting point at about 3200? +/- 1300?F. Because of its great affinity for oxygen and combines readily with nitrogen and sulfur it is used as a deoxidizer and scavenger in steel making. It is used as an alloy with nickel for cutting tools and is used in copper alloys. |
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