A test designed to assess the value of antifouling compositions by
measuring the rate of loss of toxic ingredients from a painted surface
during immersion in seawater. Osborne
Material sufficiently mineralized to be economically recoverable by
selectively dissolving the wanted mineral in a suitable solvent.
See also:leaching
Mineralized materials stacked so as to permit wanted minerals to be
effectively and selectively dissolved by application of a suitable solute.
A mixed method of chemical reaction plus flotation developed for such
copper ores as chrysocolla and the oxidized minerals. The value is
dissolved by leaching with acid, and the copper is reprecipitated on
finely divided particles of iron, which are then recovered by flotation,
yielding an impure concentrate in which metallic copper predominates.
Abbrev., L.P.F. Pryor, 3
a. A bluish-white metal of bright luster, very soft, highly malleable,
ductile, and a poor conductor of electricity; very resistant to corrosion;
a cumulative poison. Symbol, Pb. Rarely occurs in native form; chiefly
obtained from galena (PbS). Lead is used in storage batteries, cable
covering, plumbing, ammunition, antiknock gasoline, radiation shielding,
and to absorb vibration. Other lead compounds are used in paints, fine
glass, and lenses. Environmental concern with lead poisoning has resulted
in a U.S. national program to reduce the concentration of lead in
gasoline. Handbook of Chemistry and Physics, 3
b. An open watercourse, usually artificial, leading to or from a mill,
mine, or reservoir. Syn:leat
c. See:ledge; lode. CF:blind lead
d. A placer deposit. CF:blue lead; deep lead. Pron. leed.
e. A defined gutter of auriferous wash. Pron. leed. Gordon
f. A track haulage term for the distance from the point of a frog to the
point of the switch. Pron. leed. Kentucky
g. A term sometimes used for the distance between the sheave and the
winding drum centers. The greater the lead, other things being equal, the
smaller the fleeting angle. Too great a lead results in vibration and
whipping of the rope between sheave and drum. Idler or sag rollers are
frequently installed where long leads are necessary. Pron. leed.
Nelson
h. The distance a bit is held suspended off bottom in a borehole before
rotation and downward movement of the drill string is started. Pron. leed.
Long
i. Commonly used synonym for ledge or lode. Many mining location notices
describe the locator's claim as extending a certain number of feet along
and so many feet on each side of the lode, lead, vein, or ledge. Thus
Lead, S. Dak., was so named because of the Homestake lead. Blind lead: A
lead or vein that does not outcrop or show at the surface. Used esp. at
Virginia City, NV. CF:lode
j. Properly, placer gravels. Blue lead: A Tertiary river channel at
Placerville, CA. So called because of the bluish-gray color of the
gravels. Deep lead: Goldbearing gravels deeply covered with debris or lava
applied particularly to those of Victoria, Australia. Pron. leed.
Fay
k. The longitudinal distance traveled in one revolution by a spiral thread
or screw. Pron. leed. Long
A secondary cell battery with an electromotive force of about 2 V. It is
suitable for work where a steady voltage is required, and extensively used
for motor car lighting, miners' safety lamps, shuttle cars, and battery
locomotives. Morris
The distance coal has to be hauled from the mine to its place of shipment.
Standard, 2
A nitrite of lead, Pb(N3 )2 , used as an initiating
explosive in blasting caps.
A furnace in which gold or silver ores are smelted with lead.
Standard, 2
In the separation of the noble metals from their impurities, lead is fused
with the ore. The bullion so formed drops to the bottom of the crucible in
the lead button from which the precious metal is extracted by cupellation.
Syn:crucible assay
See:cerussite; white lead ore.
The surfaces or inset cutting points on a bit that face in the same
direction as the rotation of the bit. Long
a. A narrow vein branching upwards at an angle from a much larger vein.
See also:dropper
b. A thin layer of coal, coaly shale, or ironstone that serves as a guide
or datum toward workable beds in a mine.
Guides in a pile frame to take the drop hammer of a pile driver.
Hammond
Synthetic PbAl2 Si2 O8 .
The fume escaping from lead furnaces and containing both volatilized and
mechanically suspended metalliferous compounds. Fay
See:galena
A monoclinic mineral, 8[Pb4 (SO4 )(CO3 )2 (OH)
2 ] ; trimorphous with macphersonite and susannite; soft; may
fluoresce yellow; in oxidized zones of lead-ore deposits.
The one of a pair of parallel headings that is kept a short distance in
advance of the other. This may be adopted to drain the water and thus
secure one dry heading. The term is also applied to a heading that is
driven in the solid coal in advance of the general line of face.
Nelson
Scot. A working place in advance of the others, such as a heading or a
level. Fay
Derb. Small sparry veins in the rock. Syn:leader