Octahedra Sentence Examples
By heating a mixture of cobalt oxalate and sal-ammoniac in air, it is obtained in the form of minute hard octahedra, which are not magnetic, and are only soluble in concentrated sulphuric acid.
This solution, on standing, deposits octahedra of the composition CoC1 2.6NH 3.
Many of them contain large octahedra of magnetite.
It crystallizes in octahedra isomorphous with stannic oxide.
Lead monoxide is dimorphous, occurring as cubical dodecahedra and as rhombic octahedra.Advertisement
They are soluble in water, have an astringent, acid, and sweetish,, .taste, react acid to litmus, and crystallize in regular octahedra.
It may be obtained as jet black octahedra (isomorphous with thoria) by fusion with borax.
Uranous chloride, UC14, was first prepared by Peligot by heating an intimate mixture of the green oxide and charcoal to redness in a current of dry chlorine; it is obtained as sublimate of black-green metallic-looking octahedra.
Stannic iodide, Sn14, forms red octahedra and is prepared similarly to stannic bromide.
Potassium osmiate, K 2 0sO 4 2H 2 0, formed when an alkaline solution of the tetroxide is decomposed by alcohol, or by potassium nitrite, crystallizes in red octahedra.Advertisement
It crystallizes in dark red octahedra which are almost insoluble in cold water.
It may be obtained crystallized in quadratic octahedra of a greenish-blue colour, by melting in a sealed tube containing an inert gas, and inverting the tube when the metal has partially solidified.
The salt K2S03 2H20 is obtained as oblique rhombic octahedra by crystallizing the solution over sulphuric acid.
It forms red octahedra and is less soluble in water than the corresponding potassium compound.
It crystallizes in red octahedra and dyes silk and wool yellow.Advertisement
Octahedra having triangular faces other than equilateral occur as crystal forms. See Polyhedron and Crystallography.
It crystallizes in the cubical system, often in beautiful octahedra and rhombic dodecahedra.
It crystallizes in the cubic system, usually in cubes, pentagonal dodecahedra or octahedra, often of great beauty and perfection.
On account of their resemblance to the twins of the mineral spinel (which crystallizes in octahedra) these are ?i D known as " spinel twins."
Halite or rock-salt crystallizes in the cubic system, usually in cubes, rarely in octahedra; the cubes being solid, unlike the skeleton-cubes obtained by rapid evaporation of brine.Advertisement
Thallous fluoride, T1F, forms white glistening octahedra; it is obtained by crystallizing a solution of the carbonate in hydrofluoric acid.
Fine yellow fluor-spar occurs in some of the Saxon mines, and beautiful rose-red octahedra are found in the Alps, near Goschenen.
Silver peroxide, AgO, appears under certain conditions as minute octahedra when a solution of silver nitrate is electrolysed, or as an amorphous crust in the electrolysis of dilute sulphuric acid between silver electrodes.
Silver fluoride, AgF, is obtained as quadratic octahedra, with one molecule of water, by dissolving the oxide or carbonate in hydrofluoric acid.
The fracture is distinctly crystalline; large crystals, either regular dodecahedra or octahedra, may be obtained by crystallization from carbon bisulphide, sulphur chloride, &c., or by sublimation.Advertisement
The perfectly pure metal may be prepared by heating the oxide or oxalate in a current of hydrogen; when obtained at a low temperature it is a black powder which oxidizes in air with incandescence; produced at higher temperatures the metal is not pyrophoric. Peligot obtained it as minute tetragonal octahedra and cubes by reducing ferrous chloride in hydrogen.
Calcium ferrite, magnesium ferrite and zinc ferrite, ROFe203(R=Ca, Mg, Zn), are obtained by intensely heating mixtures of the oxides; magnesium ferrite occurs in nature as the mineral magnoferrite, and zinc ferrite as franklinite, both forming black octahedra.
Pyrite may be prepared artificially by gently heating ferrous sulphide with sulphur, or as brassy octahedra and cubes by slowly heating an intimate mixture of ferric oxide, sulphur and salammoniac. It is insoluble in dilute acids, but dissolves in nitric acid with separation of sulphur.
Ferric potassium sulphate, the common iron alum, K2SO4Fe2(SO 4)3.24H2O, forms bright violet octahedra.
By sublimation in a current of hydrogen it can be crystallized in the form of regular octahedra; it is slightly harder than tin, but is softer than zinc, and like tin, emits a crackling sound when bent.