38 University Geological Survey of Kansas. 
Zine. 
METALLIC ZINC. 
Metallic zinc is a white metal, lustrous and opaque, and 
capable of receiving a high polish. Ordinarily speaking it is 
not malleable or ductile, but rather brittle. There is a cer- 
tain temperature, however, at which it is both malleable and 
ductile, and consequently can be rolled into thin sheets, pro- 
ducing the sheet zinc of commerce. If heated to a tempera- 
ture a little higher it again becomes brittle and incapable of 
treatment in rolling mills. The temperature at which it may 
be rolled into thin sheets lies between 100 and 150 deg. C. 
At about 200 deg. C it again becomes brittle and fuses at 
410 to 430 deg. C. If the heat is carried still higher it vola- 
tilizes at 1000 deg. C. Its hardness is 2; that is, itis a little 
harder than lead, and yet quite softer than copper. Its spe- 
cific gravity is 7.17. Zinc crystallizes readily in the rhombo- 
hedral system and apparently also in the regular system, 
especially in some of its alloys. 
Zinc is used for many purposes, the most important of 
which is galvanizing iron to protect the iron from rust. A 
polished surface of zinc tarnishes rapidly when exposed to 
the air, by the forming of zinc oxide. This coating of oxide 
soon forms a compact covering which shuts out all air and 
effectively prevents further oxidation. Zinc readily forms 
an alloy with iron. By dipping a piece of iron into a bath 
of molten zinc a thin film of zinc is left on the surface of the 
iron. On exposure to the weather the zinc film soon becomes 
covered with a coating of zine oxide, as above explained, 
which protects the entire mass from further weathering. 
Such a use of zinc has become very extensive, and at the 
present time more than half the zinc of commerce is con- 
sumed in this way. 
Zinc is rolled into thin sheets and used largely in that form 
for various purposes, such as metals to place under stoves in 
residences and business houses, to be cut into fine shreds for 
use in the cyanide process for extracting gold and silver, and 
in Europe extensively for roofing. It is not used for roofing 
to any considerable extent in America, but many people 
