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ORCHIL

A dye prepared from certain lichens by treatment with a solution of potash or milk of lime, from which extracts the “colouring acids” are precipitated by the action of hydrochloric or acetic acid. “French purple” is an orchil dye.

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OLIVINE

A mineral magnesium silicate with varying amounts of ferrous silicate 2Si04.

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OSMIUM

Atomic weight, 191 sp. gr., 2247; meltingpoint, 2,700 degrees C. A rare element of the platinum group, and the most refractory; found in alloyed association with iridium in certain platinum ores, and notably in socalled osmitidium, in parts of which the osmium content runs as high as from 30 to }.o per cent. It is a hard, bluishwhite, and the heaviest known metal, possessing catalytic properties. It can be prepared from its oxides by reduction; is known in crystalline and amorphous forms, and burns brightly when strongly heated, forming osmium tetroxide. The amorphous variety is dissolved by aqua regia and the tetroxide is thus produced, but the compact form is insoluble in all acids. Four oxides are knownviz., OsO, 0s203, 0s02, and OsOt and there are salts corresponding to the sesquoxide. Three chlorides are knownOsCl2, OsCl3, and OsCl4.

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OXIMES

A series of bodies obtained from aldehydes and ketones by condensation of the carbonyl group with the compound hydroxylamine.

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OPOPANAX

A resinous gummy substance from the roots of Pastmaca opopanax growing in warm climates. The dried juice from Turkey and the East Indies is brought in lumps which have a peculiar odour and a bitter acrid taste. It is used in perfumery.

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ORGANIZED

Arranged in definite form or structure, such as cells, fibres, membranes, hair, skin, etc.

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OIL CAKE

The cake remaining after the expression of oils from seeds. Homemanufactured Cakes and Meals.Linseed cake containing not less than 8 per cent, oil, cottonseed cake, undecorticated groundnut cake, semidecorticated groundnut cake, decorticated groundnut cake, palmkernel cake, rape cake, copra cake, sesame cake, soya cake, extracted palmkernel meal, extracted rape meal, extracted soya meal. Imported Cakes and Meals.North American linseed cake, Argentine linseed cake, Canadian linseed cake, Australian linseed cake, Spanish and Portuguese linseed cake, Egyptian cottonseed cake, decorticated cottonseed meal, decorticated cottonseed cake, repressed cotton cake, semidecorticated cotton cake, copra cake, palmkernel cake, Rangoon rice meal, Italian rice meal, Canadian rice meal, Egyptian rice meal, gluten feed, maizemeal cake. The feeding values of cakes are chiefly represented by their protein constituents.

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OXALATES

Compounds of oxalic acid with metals and bases. The alkaline oxalates are soluble in water, but the others are for the most part insoluble.

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OXYHYDROGEN FLAME

Produced by burning a mixture ot oxygen and hydrogen gases until superseded by the electrir furnace it was used, amongst other purposes, for the manufacture of artificial rubies and sapphires. Its temperature is in the neighbourhood of 2,800 degrees C.

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OXYGENATED WATER

Water mechanically charged with oxygen gas and not to be confounded with hydrogen dioxide.

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