CHLORINE is an elementary gaseous body discovered by Scheele, in 1774. It has a very powerful and disagreeable odour, is very suffocating, even when considerably diluted with air, and its taste is astringent. Faraday has shown that, when this gas is subjected to a pressure of about four atmospheres, and kept cool, it is condensed into a yellow limpid fluid, which is extremely volatile, and, when the pressure is removed, rapidly reassumes the gaseous form. Neither light, heat, nor electricity produces any change in the pro perties of chlorine gas, provided it be dry ; but, if it be moist, then light causes it to decompose the water.
One of the most curious and important pro perties of chlorine is the power which it pos sesses of destroying the colour of animal and vegetable matter in general, and hence its ex tensive application to the purpose of bleach. ing. [BLEsciania.] This is effected how ever not by dry chlorine, but when moisture is present. Chlorine is a powerful supporter of combustion : if certain metals, and espe cially antimony, in the state of powder, be thrown into chlorine gas, they burn spontane ously; phosphorus also exhibits similar phe nomena. Chlorine is a powerful disinfectant ; Sir William Burnett's ' Disinfecting Fluid' consists of chloride of zinc. Mr. F. Smith has recently (1847) introduced a small appa ratus for making chlorine, to be used in hos pitals, or houses, or rooms, where the air is likely to be tainted.
Many of the compounds of chlorine with other substances are highly important. The most so perhaps is Aforiatic or Hydro-chloric Acid, which consists of chlorine and hydrogen ; it is a colourless gas, with a pungent odour and an acrid taste; it extinguishes burning bodies, and excites coughing ; it is expanded by heat, and decomposed by electricity; it readily absorbs atmospheric moisture, and then becomes liquid mmiatio acid, which has the smell and acid properties of the gas.
Muriatic acid is largely used in chemistry and the arts. When it is mixed with nitric acid, it is decomposed, and a solution of chlo rine is obtained, which, under the old name of aqua regia or modern name of nitro-muriatic acid, is used for dissolving gold and platinum.
The manufacture of chlorine at the Felling Chemical Works, near Newcastle, according to the patent obtained by Mr. Lee in 1842, is conducted as follows :—Each of the chambers for the manufacture is covered by an arch, over which the furnace flue is led, so that the heat may be transmitted downward through the arches to the materials placed within the chambers. In each chamber is a stone trough, such as is used for the condensers and flues of alkali works. One side of each chamber is furnished with a leaden door, and at the opposite side is a pipe of lead or of earthen. ware for the escape of the chlorine. The fire being kindled, and the chamber sufficiently heated, lumps of manganese are placed in the troughs, and the doors closed; muriatic acid is then introduced through glass tubes, con veniently placed for that purpose. The chlo rine is speedily given off, and passes into an other chamber ; and the muriate of manga nese is drawn off from the troughs on the completion of the process by means of syphons.