The difference between the actual electrode potential, when appreciable
electrolysis begins, and the reversible electrode potential.
ASM, 1
Relay that serves primarily the same purpose as an overcurrent relay
except that it is connected in the line by a potential transformer which
measures the voltage across the line. When an overvoltage exists the relay
operates and opens the circuit breaker. Coal Age, 3
a. To hoist a cage into or over the top of a headframe. Syn:overtravel
Fay
b. In hoisting through a mine shaft, failure to bring a cage or skip
smoothly to rest at the proper unloading point at the surface. If severe,
it can lead to a serious accident unless the special preventive devices
function effectively. Overwind can also cause a cage to be lowered into
the sump at the bottom of the shaft, also with serious consequences.
Pryor, 3
One of the best known overwinder prevention devices consists of two
vertical-screwed spindles, each carrying two traveling nuts and chain
driven from the drum shaft so as to rotate in opposite directions. The
nuts are prevented from rotating by projections engaging with a fixed
plate and therefore travel up and down according to the movement of the
cages. The upper nut takes care of overwinding and the lower nut of
overspeeding. Mason
a. A term applied to a continued pull on the hoisting rope of a cage,
after the cage has reached the top of the shaft. The result of this
carelessness, or accident, is a broken hoisting rope and all the danger
that implies. Stauffer
b. A rope or cable wound and attached so that it stretches from the top of
a drum to the load. Nichols, 1
A switch that may be used on winders, or haulages, to cause the power to
cut off from the driving motor, or engine, and the brakes to be applied.
Such a switch may be: (1) situated in the headgear and operated by the
conveyance, (2) mounted on the automatic contrivance, or (3) operated by
the depth or distance indicator. BS, 13
See:oolith
A flotation process involving the violent agitation of the pulp in cold
water to which a small percentage of eucalyptus oil, about 62.5 g, is
added. Fay
Owen's borehole surveying instrument
A clockwork photographic apparatus that records clinometer and compass
readings on sensitized paper. It is used during borehole surveying.
Hammond
An instrument similar to the konimeter but differing in that the air to be
sampled undergoes humidification prior to being blown through the jet. The
velocity of impingement is about 200 to 300 m/s and the jet is rectangular
instead of circular. The prior humidification of the air causes
condensation of moisture upon the dust particles by super saturation due
to the pressure drop at the jet, and so assists in the deposition and
retention of the particles on the slide. The Bausch and Lomb dust counter
is the American counterpart of this instrument. Osborne
See:whewellite
See:humboldtine
An orthorhombic mineral, (NH4 )2 C2 O4 .H (sub
2) O ; transparent; yellowish-white; forms lamellar and pulverent masses
in guano.
A variety of aliphite hydrocarbon containing oxygen; light-yellow; soft.
Tomkeieff
Sediment composed of the oxides and hydroxides of iron and manganese,
crystallized from aqueous solution. It is one of Goldschmidt's groupings
of sediments or analogues of differentiation stages in rock analysis.
AGI
a. The firing of a kiln in such a manner that combustion is complete and
in consequence the burning gases are amply supplied with oxygen, which
causes metals in clay and glazes to give their oxide colors.
ACSG, 1
b. Combination with oxygen; increase in content of a molecular compound;
increase in valency of the electropositive part of compound, or decrease
in valency of the electronegative part. Pryor, 3
c. A reaction in which there is an increase in valence resulting from a
loss of electrons. CF:reduction
d. In fuel practice, the combination of oxygen with a substance, with or
without the production of food. Francis, 2
The absorption of oxygen from the air by coal, particularly in the crushed
state; this engenders heat which can result in fire. Ventilation, while
dispersing the heat generated, supports oxidation that increases rapidly
with a rise in temperature. Fresh air should not gain access to the coal.
See also:gob fire
A compound of oxygen with another element. CTD
Discoloration of a metal surface caused by oxidation during thermal
treatment. Light Metal Age
A mineral formed by the union of an element with oxygen; e.g., corundum,
hematite, magnetite, and cassiterite. Leet, 1
An iron ore with oxygen as its main impurity; also iron rust.
Mersereau, 2