Page:The American Cyclopædia (1879) Volume IV.djvu/513

 CHLOKATES CHLORINE 501 minum. It has been prepared as an antiseptic and disinfectant, and also for use in medicine. CHLORATES, monobasic salts of chloric acid, H010 3, having the general formula M010 8. They are all soluble in water, and are trans- formed by heat into oxygen and a metallic chlo- ride. The only one which possesses much im- portance in medicine or the arts is the potas- sium chlorate, which will be treated of with the salts of that metal. CHLORIC ETHER, a name sometimes given to Dutch liquid, or bichloride of ethylene, and also erroneously applied to chloroform by its discoverer, Mr. Guthrie of Sackett's Harbor. At present it is applied to the preparation of- ficinally known as spiritus chloroformi, and composed, according to the " United States Dispensatory," of one measure of chloroform in between eight and nine of strong alcohol. A "strong chloric ether," which consisted of one part chloroform and two of alcohol, was used by Dr. John 0. "Warren of Boston by inha- lation, as an anaasthetic in some 50 cases, and was supposed by him to be safer than chloro- form. But in fact it possesses no advantages over the more commonly used anaesthetics, and it is at present but little employed for that purpose. The officinal preparation is a conve- nient one for the internal exhibition of chloro- form, the effect of which is perhaps slightly modified by the stimulant action of the al- cohol it contains. Half a dram to a dram may be given (diluted with water) as a dose. If the British preparation of chloric ether, which contains much less chloroform than the American, be used, the effect of the alcohol will be more marked than that of the chloro- form. As a sedative and mild anodyne, chloric ether may be used with advantage in nervous restlessness, sleeplessness, and spasmodic af- fections, especially of the air passages. CHLORIMETRY, a process chiefly designed to estimate the commercial value of bleach- ing powder. As this value depends upon the quantity of chlorine which can be liberated from the powders by an acid, Gay-Lussac pro- posed to estimate the value by measurement of the bulk of a solution of indigo of known strength which a given weight of the chloride is able to deprive of its blue color ; and subse- quently he determined the amount of avail- able chlorine by the quantity of a standard solution of arsenious acid which could be con- verted by a known weight of the bleaching powder into arsenic acid. A still more con- venient plan has been described by Graham. It depends upon the determination of the quan- tity of a ferrous salt which a given weight of bleaching powder, in the presence of an ex- cess of acid, can convert into a ferric salt. To perform the operation, a tall narrow tube, called a burette, capable of holding 1,000 grains of water, and graduated into 100 equal parts from above downward, is employed. CHLORINE (Gr. ^Aw/xS?, green), a gaseous chemical element of yellowish green color, dis- covered by Scheele in 1774, called dephlogisti- cated marine acid air, also oxidized muriatic acid, and first pronounced a simple body by Gay-Lussac and Thenard in 1809 ; a conclusion afterward confirmed by Sir Humphry Davy, who gave it the name it now bears. It occurs very abundantly disseminated over the earth, in salt brines in combination with sodium, with cop- per as atacamite, with potassium as sylvine, with silver as horn silver, with mercury as native calomel, and in smaller quantities with other minerals and volcanic gases. In the animal kingdom it is found in the gastric juice, in perspiration, &c., and among vegetables in marine plants. It is therefore one of the most abundant constituents of the earth. For lab- oratory use it can be conveniently prepared by heating in a retort a mixture composed of 10 parts by weight of common salt, 8 parts of manganese dioxide, and 24 parts of sulphuric acid, diluted with 12 parts of water. On a large scale it is usually prepared from hydro- chloric acid, which in England is an incidental product. According to Weldon's process, the crude muriatic acid of the soda ash manufac- tory is decomposed by manganese dioxide, and the resulting manganese chloride is regenerated to be employed again. Deacon has modified the operation by conducting the muriatic acid di- rectly from the condensing towers into a rever- beratory furnace along with some oxygen of the air, over bricks saturated with salts of copper. Chlorine is liberated, and the reaction is said to be continuous, as the same copper salt will decompose an indefinite amount of the acid. Enormous quantities of chlorine are thus made in England, to be chiefly used in the manufac- ture of bleaching powders. Chlorine is a yel- lowish green, pungent, suffocating gas ; specific gravity compared to air, 2 '44, 36 times heavier than hydrogen. Under four atmospheres of pressure it can be condensed to a yellow lim- pid liquid of specific gravity 1'33. Copper, previously heated, burns readily in chlorine; arsenic, antimony, and phosphorus ignite spon- taneously. A lighted candle gives off copious volumes of smoke and is soon extinguished ; and ignited charcoal also ceases to burn on account of the weak affinity of carbon for chlorine ; but hydrogen gas burns readily in chlorine, producing effects similar to those attained by the oxyhydrogen blowpipe. A piece of paper previously saturated with turpentine bursts in- to flame when plunged into a jar of chlorine gas. The affinity of chlorine for hydrogen is so powerful that if the two gases be mixed in the dark and subsequently exposed to the solar rays, they unite with a loud explosion. The electric light, or burning magnesium, can be substituted for the sunlight in this experiment. Water at 60 F. absorbs twice its volume of chlorine gas; and if the mixture be exposed to cold, crystals of a hydrate of chlorine will form, which resemble ice excepting in crys- talline form, and contain variable quantities of chlorine according to the circumstances of