Page:The New International Encyclopædia 1st ed. v. 04.djvu/774

CHLORIMETRY. 676 CHLOROFORM. I ous acid into arsenic acid, or a known amount of ferrous salt into ferric salt; or else in de- termining the quantity of iodine which will be liberated by a given amount of bleaching-powder from a standard solution of potassium iodide. The first of these methods, originally proposed by Gay-Lussac, is applied in the following man- ner: A solution of arsenious oxide and hydro- chloric acid is prepared of knowii strength, as one in which a cubic centimeter requires for its conversion into arsenic oxide 0.01 gram of chlorine. A known amount of the bleaehing- ])owder is then mixed with water, made up to a given quantity, and poured from a burette into the arsenious oxide solution, which has been colored blue by adding a drop of indigo. The disappearance of the blue color indicates that the arsenious acid has been entirely converted into arsenic acid, and the amount of chlorine may then be determined from the quantity of bleach ing-po-Ader solution used. CHLO'EINE (from G<:.x^<Jpk,cMdros, green- ish-yellow). A gaseous element discovered by Scheele in 1774. It was supposed by its dis- coverer to be hydrochloric aeid deprived of phlogiston, and was called by him dephlogisti- cated marine aeid gas. In 178.5 Berthollet ad- ^•anced the view that this gas should be regard- ed as a compound of hydrochloric acid with oxygen, and this view was universal!}' main- tained for nearly a quarter of a century. The error was first pointed out by Gay-Lussac and Thenard in 1809, and in the following year Davy demonstrated clearly the elementary na- ture" of the gas, which he named chlorine. It is never foimd free, but occurs extensively in the form of chlorides, as in the mineral halite, or rock salt, and in sea -water; in sylvite (potas- sium chloride) ; in cerargj'rite (silver chloride) ; also as alkaline chlorides in plants and animals. It may be readily prepared by the action of hy- drochloric acid on manganese dioxide, the chlo- rine' gas thus produced being washed by passing through a small quantity of water and drying with sulphuric aeid. Commercially it is ob- tained by passing over heated bricks a mixture of air and hydrochloric acid, the oxidation of the latter giving rise to the formation of free chlorine, which is then utilized for the manufac- ■ture of bleaching-powder (q.v.). Chlorine (symbol, CI; atomic w'eight, 35.45) is a greenish-vcllow gas with an irritating odor. It is liquefied" at 15° C. (59° F.), under a pres- sure of four atmospheres, yielding a dark-yellow liquid heavier than and not miscible with water. Chlorine is a non-conductor of electricity, and is exceedingly poisonous ; it attacks the mucous membranes, causing much irritation, and if in- haled is capable of causing death. It dissolves in half its volume of cold water, yielding a solu- tion that resembles the gas in color, odor, and other properties. It finds important applica- tion in the arts as a bleaching agent, and is very extensively used in cotton and paper indus- tries. Its bleaching action is due to the readi- ness with whieh it combines, in the presence of water, with the hydrogen of the coloring mat- ter. This avidity for the hydrogen of organic matter may be demonstrated by introducing a lighted taper into an atmosphere of chlorine — the taper will continue to burn, its hydrogen combining with the chlorine, while its carbon is liberated in the form of .soot. Chlorine is also a powerful disinfectant and deodorant, and is much used for the destruction of the poisonous germs of infectious diseases. In chemical proc- esses chlorine is frequently used as an oxidizer. Chlorine combines readily with basic radicals to form chlorides. Its most important com- pounds are described under Salt; Hus.^ciiixg- I'owuEii; IIydhoohlokic Acid, etc. Consult Eichardson and Watts, Treatise on Aeids, Alka- lies, and f<alts (London, 1863-67) ; also au- tliorities referred to under Ble.ciii>'G. CHLO'RIS (Lat., from Gk. XXuipU ). (1) The (ireek goddess of flowers, identified with the Ro- man goddess Flora. (2) One of the daughters of the Theban Amphion and Niobe. She and her brotiier Amyclas w'crc the only children of Niobe, who escaped being slain by Apollo and Artemis. (3) The daughter of Amphion of Orchomenos, and the mother of Nestor. CHLO'RITES (from Gk. x^"P^S, chloros, greenish-yellow). A group of minerals cr'staUiz- ing in the monoclinic system and related to the micas. They are silicates of aluminum, mag- nesium, and ferrous iron — the latter constituent causing the characteristic green color — and also contain chemically combined water in varying proportions. The aluminum may be replaced partially by ferric iron. They occur as distinct crystals, or in the form of fibres and scales, which possess a well-marked cleavage. The chlo- rites are visually secondary minerals — i.e. they have been formed by the alteration of other magnesium silicates, such as garnet, amphibole, pyroxene, biotite, etc. This process of alteration, commonly called cliloritization, may be frequently obsoi--ed among the older rock formations. (See Chlorite Schist, and Metamorpiusm.). In chemistry the name chlorites is applied to the salts of chlorous acid. CHXORITE SCHIST, klo'rit shist. A foli- ated rcK^k containing more or less chlorite in parallel plates. Associated with the chlorite may be quartz and feldspar in considerable quan- tity, hornblende, talc, mica, iron ores, and a great variety of the rarer minerals. Chlorite varies in quantity from an exceedingly small amount to predominance. Chlorite schists are metamorphic rocks resulting from the alteration of almost any rock of appropriate composition. The chlorite may replace biotite in biotite schists, or, under proper conditions of pressure, temperature, etc., it may crystallize out from a rock originally containing no chlorite. See Chlorite; Metamorpiiism. CHLO'ROFORM (from chlorine + formyl), or TRiciii.or.o.METiiAXE, CHCl,. A colorless, heavy liquid h.aving a sweetish, ethereal odor and a sweetish, burning taste. It does not mix with wa- ter, but dissolves freely in alcohol and ether. Its specific gravity at 15° C. is 1.498, and it boils at 61° C. It is an excellent solvent for a variety of substances, such as camphor, iodine, sulphur, phosphorus, resins, fats, alkaloids, etc. It is chieliy used, however, as an ana'sthetic. It is formed bj' the direct action of chlorine on meth- ane, or marsh gas, in sunlight : further, by the ac- tion of sodium or potassium hydroxide on chloral (q.v.). The method usually employed in making chloroform on a large scale consists in distilling from iron retorts a mixture of bleaching-pow- der, water, and ordinary alcohol, or preferably