Chlorine

(klo'rin.) [Gr. chloros, green.] (Chem.) A yellowish-green gas, of a very pungent and suffocating odor. It di olves in half its volume of water, forming a faint yellow solution. When pa ed into water which is near the freezing-point, a Hydrate of C. separates in crystals. In its chemical properties, C. is very energetic, uniting directly with many other elements, sometimes with incandescence, as, for instance, with phosphorus, arsenic, antimony, .; and also with many organic compounds, its principal action being to unite with hydrogen to form hydrochloric acid. Its affinity for hydrogen is one of its strongest characteristics; it decomposes water with separation of oxygen, and thus indirectly acts as a powerful oxidizing agent; hence C. is of great value in destroying organic coloring and other matters, and also as a bleaching agent and disinfectant. C. is prepared by oxidizing hydrochloric acid, by heating it with bin oxide of manganese. Sp. gr. 2.5; at. weight 35.5. When condensed by a pre ure of four atmospheres it becomes a yellow liquid of sp. gr. 1:33. Symbol, Cl. The compounds of C. are very numerous and important; some of those which are not described below will be found under the name of the other elements of the compound. -Hypochlorous acid is a pale reddish yellow gas. When slightly heated it decomposes with explosion; it di olves in water, forming a yellowish solution, with an acid reaction; it po e es strong bleaching properties. Form. Clo. It unites with bases to form salts, three of which, the calcium, sodium, and pota ium salts, are of great use as bleaching substances and disinfectants.-Hypochlorite of Calcium, known as Chloride of lime, is a dry white powder, of a peculiar chlorous smell, and strong bleaching and disinfecting properties. It is formed, on a large scale, by pa ing C. gas over slaked lime to saturation. Form. CaO Clo. Hypochlorite of Sodium is a mixture of hypochlorite and chloride of sodium; it is prepared by pa ing C. gas through caustic soda.-Hypochlorite of Pota ium, or Eau de Javelle, is prepared in a similar manner, and is greatly used for bleaching.- Chloric acid is a colorle syrupy liquid, strongly acid, and very powerful as an oxidizing and bleaching agent. Form. Clog. With bases it forms salts, which are decomposed by heat with evolution of oxygen, and detonate when heated with combustible bodies; the most important of these are: Chlorate of Barium, forming large prismatic colorle crystals, which decrepit ate and melt when heated to a temperature approaching redne . This salt is much used in pyrotechny, and it produces an intense green light when it is heated with sulphur or other combustibles. Form. BaO.Clo.- Chlorate of Pota ium crystallizes in large six-sided plates. It is largely used in laboratories as a source of oxygen gas. When mixed with combustible substances such as sulphur, antimony, or phosphorus, and struck with a hammer, the mixture detonates; when mixed with some other combustibles, and touched with a drop of concentrated sulphuric acid, the whole ignites with a bright flash; when added to strong sulphuric acid, gaseous peroxide of C. is given off, which ignites combustible bodies. This salt is largely used as an oxidizing agent in the laboratory, and in some manufacturing operations, in calico printing, for instance; and it is also used in the manufacture of lucifer matches, fireworks, and percu ion - caps. Form. KO.Clog.-Perchloric acid, in the pure state, is a colorle oily liquid, very volatile, and easily decomposed. It is, perhaps, the most powerful oxidizing agent known; a single drop brought in contact with charcoal, or other combustible body, induces combustion with explosive violence. Sp. gr. 1.782. Form. Clo7. It unites energetically with water, forming a hydrate, which is a white solid crystalline substance, almost as violent in its oxidizing powers as the anhydrous acid.- Chlorides. C. unites with almost every element, and with numerous organic compounds. All chlorides of importance will be found under their respective names.- Chlorhydric acid. See HYDROCHLORIC ACID. [s. 181]