Page:The American Cyclopædia (1879) Volume III.djvu/786

 77G CARBURETTED HYDROGEN CARCASSONNE tingnished as light carburetted hydrogen, and the other as olefiant gas. The former is the fire damp of miners, also called marsh gas, &c. It was observed in coal mines as early as 1640. Dr. Franklin in 1774 called the attention of Priestley to an inflammable gas obtained in this country by stirring stagnant pools. It was first accurately described by Drs. Dalton and Thomson in 1811. It is a colorless gas, without taste or smell, and neither of acid nor alkaline properties. Its composition is : carbon 1 atom, hydrogen 4 atoms, OIL ; or per cent., C=75, H=25. Its weight, compared with that of air, is 0-555. Burning bodies immersed in it are extinguished, and it does not support respiration. It is highly inflammable, burning with a yellow flame ; but it requires a high heat to ignite it. United with oxygen or at- mospheric air in due proportion, a compound is produced which explodes with the electric spark or the approach of flame. The mixture of air to produce an explosion may be from 7 to 14 times that of the gas. Water and car- bonic acid gas result from the chemical change. In mines of bituminous coal this gas is generated abundantly, and it also issues from the earth in various parts of the world. The burning springs of Baku have already been noticed in the de- scription of that place. Similar springs are met with in western New York, Pennsylvania, and Virginia ; and the gas from some of these is used for illuminating purposes. The prin- cipal interest that attaches to this gas is owing to the terrible explosions it has caused in the English coal mines, which led Sir Hum- phry Davy and George Stephenson to in- vestigate its properties with a view of dis- covering some method of protecting the mi- ners. Thus the safety lamp was discovered, which still continues to be the most valuable guard next to thorough ventilation. Olefiant gas, the other variety of carburetted hydrogen, was discovered by some Dutch chemists in 1796, who gave it this name in consequence of its forming an oil-like liquid with chlorine. It consists of 85-71 per cent, of carbon and 14-29 of hydrogen, and is properly represented by the symbol CjH<. Its specific gravity is very near that of atmospheric air, being estimated at 0-967. The gas possesses an odor slightly ethereal. Burning bodies are extinguished and animals cease to breathe in it. It burns with a dense white light. Mixed with three or four volumes of oxygen or 10 or 12 of air, it violently explodes by the electric spark or flame. Ex- posed to red heat in a porcelain tube, it is de- composed, charcoal is deposited, and ligbt car- buretted hydrogen or hydrogen remains. A succession of electric sparks convert it into charcoal and hydrogen, the latter occupying twice the original bulk of the gas. It is lique- fied under the pressure of 40 atmospheres, when exposed to the low temperatures attained by solid carbonic acid and ether in a vacuum. In this form it is a clear, colorless, transparent fluid. Several methods are given for obtaining it. It results from distilling coal or fat sub- stances in close vessels. Alcohol distilled with four to seven times as much sulphuric acid yields it, and the gas is purified by passing it through lime water. CAKBURIS, Marino, count, a Greek engineer, born at Argostoli, Cephalonia, at the beginning of the 18th century, died there in 1782. I It- was educated at the university of Bologna. Banished for some folly from Greece, he entered the Russian service under the name of Lascaris. The empress Catharine II. appointed him lieu- tenant colonel of the corps of engineers, and intrusted him with the construction of the work connected with the statue intended for Peter the Great. Oarburis procured a mono- lith consisting of a block of granite from the gulf of Finland, 21 ft. high, 40 ft. long, and 27 ft. wide. He invented a mechanical apparatus for removing this to St. Petersburg, which vs afterward at the request of the French govern- ment placed in the conservatoire des arti et metiers. He afterward settled in Cephalonia, and experimented in the cultivation of indigo and in the growth of sugar and American cot- ton for about four years, when he was assas- sinated by some Laconian laborers. < AK< A.IKMK, a town of Spain, in the prov- ince and 23 m. S. 8. W. of Valencia, in a beau- tiful plain on the Jucar; pop. about 9,000. It is handsome and prosperous, and has several linen and woollen manufactnries. Many Ro- man remains have been discovered in its vi- cinity. The chief trade is in silks, oranges, and pomegranates. CARCASSONNE (anc. Careaso), a city of Lan- guedoc, France, capital of the department of Aude, 60 m. S. E. of Toulouse, on the river Aude ; pop. in 1866, 22,173. The river divides it into two parts, the old city and the new, joined by a bridge of 10 arches. The new town is well built, with broad streets inter- secting each other at right angles. It is an important manufacturing and commercial centre, and contains large woollen factories, producing a fine cloth, highly esteemed for its brilliant dyes, which is especially exported to the Levant, Barbary, and South America. Trade is carried on in grain, wines, fruit, and