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olten glassy matter into a stony mass by slow cooling, the result being the formation of crystallites, microbites, etc., in the glassy base, which are then called devitrification products.

ing the plane of polarization of luminous rays toward the right hand; as, dextrorotatory crystals, sugars, etc. Cf. Levorotatory.

A sirupy, or white crystalline, variety of sugar, C6H12O6 (so called from turning the plane of polarization to the right), occurring in many ripe fruits. Dextrose and levulose are obtained by the inversion of cane sugar or sucrose, and hence called invert sugar. Dextrose is chiefly obtained by the action of heat and ac…

A basic, dark-colored, holocrystalline, igneous rock, consisting essentially of a triclinic feldspar and pyroxene with magnetic iron; -- often limited to rocks pretertiary in age. It includes part of what was early called greenstone.

The separation of different substances in solution, as crystalloids and colloids, by means of their unequal diffusion, especially through natural or artificial membranes.

h bisects a system of parallel chords drawn in a curve or surface. -- Diametral planes (Crystal.), planes in which two of the axes lie.

Having a single, distinct, diagonal cleavage; -- said of crystals. Mohs.

Having the property of dichroism; as, a dichroic crystal.

An instrument for examining the dichroism of crystals.

Having two of the intersections between the three axes oblique. See Crystallization.

Having two plane faces; as, the dihedral summit of a crystal. Dihedral angle, the angular space contained between planes which intersect. It is measured by the angle made by any two lines at right angles to the two planes.

A red crystalline nitrogenous substance or artificial production, which by reduction passes directly to indigo.

Crystallization in two independent forms of the same chemical compound, as of calcium carbonate as calcite and aragonite.

Crystallizing under two forms fundamentally different, while having the same chemical composition.

A colorless, crystalline hydrocarbon, C20H14, obtained from naphthylene, and consisting of a doubled naphthylene radical.

A crystallized variety of pyroxene, of a clear, grayish green color; mussite.

A hydrous silicate of copper, occurring in emerald-green crystals.

An igneous, crystalline in structure, consisting essentially of a triclinic feldspar and hornblende. It includes part of what was called greenstone.

A white, crystalline, nitrogenous substance obtained by the reduction of isatin. It is a member of the indol series; -- hence its name.

A white crystalline substance, C6H5.C6H5, obtained by leading benzene through a heated iron tube. It consists of two benzene or phenyl radicals united.