This gas is insoluble in water ; does not render lime-water turbid; mixed with atmospheric air no diminution of bulk en sues, but the mixture, when fixed, deto nates loudly, and deposits metallic arse nic; it has an alliaceous smell; it extin guishes burning bodies, and is fatal to animals; it is decomposed by oxygenated muriatic acid gas. if a lighted taper be immersed in a phial of this gas, it is in stantly extinguished ; but • the gas burns at the mouth of the phial with a lambent white flame, which diffuses white fumes of arsenious acid. If it be inflamed in a phial with a small orifice, the flame gra dually descends to the bottom of the phial, which becomes coated with crystallized metallic arsenic. Two parts of this gas, with one of oxygen, will explode loudly, and the products are water and arsenious acid; soap bubbles, made with a mixture of these gases, explode with a bluish White flame. Equal parts of the gases ex plode with a much more vivid flame, but less noise. A stream of this gas, burned in a large receiver filled with oxygen, emits a blue flame of uncommon splen dour. According to Tromsdorff's calcu lation, a cubic inch of the gas contains about a quarter of a grain of the arsenic. Its specific gravity is rather more than half that of atmospheric air.
GAS, carburetter! hydrogen. There are several varieties of this gas, the hydrogen holding different proportions of carbon in solution, according to the process by which it is obtained.
The gas of stagnant water, which may be procured by stirring the mud at the bottom with a stick, and collecting the gas, as it rises in bubbles, in an inverted bottle, is this compound, as is also the fire damp of coal mines. The vapour of water passed through a tube containing ignited charcoal consists of this gas and carbonic acid, which may be separated by agitating the mixture with lime diffused in water. The vapour of ether, or of al cohol, passed through a red hot tube of porcelain, coated with clay, affords the same products. If three parts of concen trated sulphuric acid, and one of alcohol, be distilled in a glass retort with a gentle heat, a carburetted hydrogen comes over. This is distinguished by the name of ole fiant gas, from its property of forming an Oil on coming into contact with oxygenat ed muriatic acid gas. If five measures be mixed with six of the oxygenated muria tic gas, as rapid a dimunition takes place as when nitrous and oxygen gases are ad ded to each other, and a thin film of oil forms on the surface of the water.
Mr. Henry examined these and some other varieties, as well as pure hydrogen, with a particular view to the light they were capable of affording; and the fol lowing arc his tabulated results: The light evolved appeared to be in proportion to the oxygen consumed, so that the first four in the list yielded very little; but the last much exceeded all the rest. Its detonation with oxygen gas too
is more violent than that of any other in flammable gas .03 of a cubic inch, with 17 of oxygen gas, beingsufficient to burst a strong glass tube.
About the year 1792, Mr. Murdoch made various experiments on the gas from coal, peat, and other substances, as a sub stitute for lamps and candles, both as fix ed and as moveable lights, and in 1793 he applied it to the purpose of lighting the extensive manufactory at Soho. Light was procured by the same means several years ago at the ovens in Shropshire, for pre paring coke and tar, on Lord Dundonald's plan. And six or seven years since a pro jector at Paris lighted up his house and gardens, and proposed to light the streets of the city in a similar way.
The varieties above enumerated differ in specific gravity, the olefiant gas being the heaviest, and that from charcoal the lightest. They differ likewise in the quantity absorbed by water, which takes up one-eighth itsbulk of olefiant gas, one sixty-fourth of that from stagnant pools, and still less of the others.
GAS. phosphuretted hydrogen. This may be procured by boding in a retort a little phosphorus, with a solution of pure pot ash. The phosphorus should be first melt ed under water in the retort, which is to be emptied when the phosphorus has con. gealed, and then filled with the alkaline solution. Of this a sufficient portion is to be displaced by hydrogen gas. Or one part of phosphorus, cut into very small pieces, and two of finely granulated zinc, may be put into ten parts of water, and six parts of concentrated sulphuric acid added ; the gas is disengaged in small bubbles, which cover the whole surface of the fluid, and take fire on reaching the air, so as form by their succession a well of fire.
If two parts of phosphiiret of lime, bro ken into pieces the size of a pea, and one of hyperoxymuriate of potash be put into an ale glass, or a Florence flask, the ves sel be filled with water, and six or eight parts of concentrated sulphuric acid be poured in through a long-necked funnel reaching to the bottom, as soon as de composition commences, flashes of fire will dart from the surface, and the bottom of the vessel will be illumined with a beautiful green light.
When phosphuretted hydrogen gas is suffered to escape into the air, as it is sues from the retort it takes fire, and a dense white smoke arises, in the form of a horizontal ring, enlarging its diameter as it ascends. It detonates when mixed sud denly with oxygen, oxygenized muriatic acid, or nitrous oxide gas. By standing it loses its property of spontaneous ascen sion, the phosphorus being deposited on the inner surface of the vessel containing it.