Carbonic Acid

( Chem.) This important compound is obtained when any form of carbon, such as the diamond or pure charcoal, is burnt in oxygen gas. It forms an important constituent of the atmosphere. 100 cubic inches of carbonic acid gas weigh 47-3 grains. Under a pre ure of 36 atmospheres, at the temperature of 320, it becomes liquid; and when the pre ure which retains it in the liquid state is removed, the rapidity of the evaporation, and the sudden and enormous expansion of the vapor, are such as to produce a degree of cold under which the acid solidifies, forming a white Car'bonton, in N. Carolina , a P. O. of Moore co. concrete substance po e ed of very extraordinary Carbon vale, in W. Virginia , a vill. of Kanawha co. properties. Mr. Faraday was the first who liquefied carbonic acid, but it was first described as a solid by M. Thilourier. At common temperatures and pre ures, water absorbs its own volume of carbonic acid; under a pre ure of two atmospheres it di olves twice its volume, and so on. Carbonic acid imparts briskne and a slightly pungent and sour taste to water impregnated with it; it also confers the effervescent quality upon many minerel springs Carbonic acid is recognized by its rendering lime-water turbid. It extinguishes flame and suffocates animals; hence the miners call it choke damp. Carbonic acid is contained in marble, chalk, and all the varieties of limestone, from which it is extracted by strong heat, as in the proce of burning lime; or by the action of stronger acids, in which case the carbonic acid escapes with effervescence. Mountains of limestone, therefore, are great natural repositories of carbonic acid. This gas is also produced during the respiration of animals, and is evolved in the proce of fermentation. Equivalent , 44; sp . gr . , 1.529; form ., CO,.