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menilite

A concretionary, opaque, dull, grayish variety of opal. Syn:liver opal
Fay

meniscus

a. The curved top surface of a liquid column. It is concave upwards when
the containing walls are wetted by some liquid (such as water in a
vertical glass tube) and convex upwards when wetted with other liquids
(such as mercury in a vertical glass tube). Webster 3rd
b. A concavoconvex lens; esp., one of true crescent-shaped cross section.
Webster 3rd

men on!

Scot. A brief expression to indicate that workers are on the cage to be
raised, or lowered, in a shaft. Fay

Menzies cone separator

Consists of a 60 degrees cone with a short cylindrical top section. It is
provided with a stirring shaft, located in its vertical axis, carrying
several sets of horizontal arms with rings of nozzles projecting through
the sides of the cone for the admission, at several horizons, of the
required water currents. At the base of the cone, a classifier column
several feet long is fitted, through which refuse discharges continuously
to an inclined refuse conveyor. Water is supplied by a centrifugal pump.
See also:cone classifier

mephitic air

a. Carbon dioxide. Webster 3rd
b. Air exhausted of oxygen and containing chiefly nitrogen.
Webster 3rd

mephitic gas

See:mephitic air

mephitis

A noxious exhalation caused by the decomposition of organic remains;
applied also to gases emanating from deep sources, such as mines, caves,
and volcanic regions. Standard, 2

merchant

A metal merchant, as distinct from a producer's agent or broker, often
acts as a principal, buying metal or concentrate from producers and others
and selling it to others. The merchant will often hold metal on personal
account while waiting for a buyer. Wolff

merchant iron

Iron in the common bar form, which is convenient for the market. Also
called merchant bar. Standard, 2

mercurial horn ore

See:calomel

mercury

a. A liquid mineral, (trigonal below -38.87 degrees C); metallic silver to
tin white; sp gr, 13.6; occurs as minute droplets in cinnabar and in some
hot-spring deposits; amalgamates with many metals.
b. Symbol: Hg. Rarely occurs free in nature. Chief ore is cinnabar, HgS .
Used in laboratory work for making thermometers, barometers, diffusion
pumps, mercury-vapor lamps, advertising signs, and pesticides. Mercury is
a virulent poison and is readily absorbed through the respiratory tract,
gastrointestinal tract, or unbroken skin.
Handbook of Chemistry and Physics, 3

mercury gatherer

A stirring apparatus that causes mercury, which has become floured or
mixed with sulfur in amalgamating, to resume the fluid condition, through
the agency of mechanical agitation and rubbing. Fay

mercury ore

Native mercury; same as cinnabar (sulfide). Dana, 3

mercury switch

A glass tube employing mercury to establish electrical contact between
circuits when the tube is tilted so that the mercury bridges the gap
between contacts, and conversely. Strock, 2

mercury-vapor lamp

Consists essentially of a sealed glass tube provided with two electrodes
and containing a gas. When an electrical potential difference is applied,
a current passes and with a suitable gas, light will be emitted. In the
case of mercury vapor, this light is of a bluish color and has proven
effective in distinguishing dirt from coal. A special starting electrode
close to one of the main electrodes initiates the discharge, and a choke
coil in series with the lamp serves to limit the current passing, since
the resistance tends to fall with increasing current. Mason

mero-

A prefix signifying part or portion. AGI

merocrystalline

See:hypocrystalline

merohedral

Any crystal form with fewer faces than the holohedral equivalent for the
crystal system. CF:hemihedral; holohedral. See also:tetartohedral

meroleims

Coalified remains of parts of plants. Tomkeieff

merosymmetric

Any crystal class with less symmetry than the distribution of points in
its lattice.

meroxene

Biotite with its optic axial plane parallel to its b crystallographic
axis.