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ontact with the air or with oxygen, it becomes reddish brown from the formation of nitric dioxide or peroxide.

Titanium dioxide occurring in acute octahedral crystals.

to combine, with oxygen; to treat with oxygen; to oxidize; as, oxygenated water (hydrogen dioxide).

ting, an acid of sulphur obtained by leading hydrogen sulphide into a solution of sulphur dioxide; -- so called because it contains five atoms of sulphur.

constructive metabolism by which carbohydrates are formed from water vapor and the carbon dioxide of the air in the chlorophyll-containing tissues of plants exposed to the action of light. It was formerly called assimilation, but this is now commonly used as in animal physiology. The details of the process are not yet…

Manganese dioxide, occurring in tetragonal crystals nearly as hard as quartz.

Manganese dioxide, a mineral of an iron-black or dark steel- gray color and metallic luster, usually soft. Pyrolusite parts with its oxygen at a red heat, and is extensively used in discharging the brown and green tints of glass (whence its name).

A form of silica, or silicon dioxide (SiO2), occurring in hexagonal crystals, which are commonly colorless and transparent, but sometimes also yellow, brown, purple, green, and of other colors; also in cryptocrystalline massive forms varying in color and degree of transparency, being sometimes opaque.…

he aggregate of those processes bu which oxygen is introduced into the system, and carbon dioxide, or carbonic acid, removed.

tallic adamantine luster, occurring in tetragonal crystals. In composition it is titanium dioxide, like octahedrite and brooklite.

ide, and now made in large quantities from phenol (carbolic acid) by the action of carbon dioxide on heated sodium phenolate. It is a white crystalline substance. It is used as an antiseptic, and in its salts in the treatment of rheumatism. Called also hydroxybenzoic acid.

Silicon dioxide, SiO

ked lime, lime slacked by exposure to the air, in consequence of the absorption of carton dioxide and water, by which it is converted into carbonate of lime and hydrate of lime.

vescence; now, in common usage, a beverage consisting of water highly charged with carbon dioxide (carbonic acid). Fruit sirups, cream, etc., are usually added to give flavor. See Carbonic acid, under Carbonic. -- Washing soda, sodium carbonate. [Colloq.]

,. It is used in cookery, in baking powders, and as a source of carbonic acid gas (carbon dioxide) for soda water. Called also cooking soda, saleratus, and technically, acid sodium carbonate, primary sodium carbonate, sodium dicarbonate, etc. -- Sodium carbonate, a white crystalline substance, Na2CO3.10H2O, having a c…

ormation of sulphur salts according to the old dual theory of salts. [Archaic] -- Sulphur dioxide (Chem.), a colorless gas, SO2, of a pungent, suffocating odor, produced by the burning of sulphur. It is employed chiefly in the production of sulphuric acid, and as a reagent in bleaching; -- called also sulphurous anhydr…

when pure, but usually yellowish or brownish, produced by the combined action of sulphur dioxide, oxygen (from the air), steam, and nitric fumes. It attacks and dissolves many metals and other intractable substances, sets free most acids from their salts, and is used in the manufacture of hydrochloric and nitric acids…

Having the characteristic odor of sulphur dioxide, or of hydrogen sulphide, or of other sulphur compounds. Sulphurous acid. (a) Sulphur dioxide. See under Sulphur. [Obs.] (b) An acid, H2SO3, not known in the free state except as a solution of sulphur dioxide in water, but forming a well-known series of salts (the sulph…

erty of crystallizing in three forms fundamentally distinct, as is the case with titanium dioxide, which crystallizes in the forms of rutile, octahedrite, and brookite. See Pleomorphism.

A process for the recovery or regeneration of manganese dioxide in the manufacture of chlorine, by means of milk of lime and the oxygen of the air; -- so called after the inventor.