GAS, oxygenized muriatic acid. This gas, which is a compound of the preceding with oxygen, presents another anomaly in the theory of acidification ; it was ob served that sulphuretted hydrogen re sembles an acid in many of its properties, though it contains no oxygen ; and we here find the radical of an acid, which, with a certain proportion of oxygen, ranks among the most powerful, so much weak ened in its properties, as even to be de. nied by some a place among the acids.
This gas is not invisible, as it has a greenish yellow colour. It has apungent, suffocating smell, and is very injurious to the lungs ; it extinguishes burning bo dies; a temperature of 40° Fahrenheit re duces it to a liquid form. Mr. Northmore condensed nearly two pints in a receiver of the capacity of 2i inches, in which state it was a yellow fluid, so extremely volatile, as to evaporate the instant the screw of the receiver was opened. A pint of this gas being injected upon half a pint of oxygen, the result was a thicker substance, that did not evaporate so soon, and left a yellowish mass behind. Nitro gen in the same proportion gave a still thicker substance, and of a deeper yel low. In both these experiments much of the grease of the machine was carried down. Into a receiver, of three inches capacity, a pint of carbonic acid gas was pumped, and then rather more than a pint of oxygenized muriatic acid gas : the result was of a sap green colour, but still elastic. Two pints of the gas with a pint of hydrogen was of a light yellow green, without any fluid, and highly destructive of colours.
This gas acts powerfully on various combustible bodies. If four parts of it, and three of hydrogen, be put into a bot tle closely stopped, inverted, with its mouth under water, and the stopple be taken out in this situation after they have thus stood twenty-four hours, nearly the whole of the gas will have disappeared, and the remainder will be absorbed by the water. The hydrogen may be com bined at once with the oxygen of this gas by the electric spark, which causes them to detonate. Phosphorus takes fire spon taneously in oxygenized muriatic acid gas; so do perfectly dry powdered charcoal of beech wood, and almost all the metals in fine filings, or very thin leaves. About a cubic inch of the gas is sufficient for a grain of metal; the bottom of the vessel should have a little sand on it, to prevent it from cracking ; and the temperature should not be less than 70°. If a drachm
of good ether be thrown into a three pint vessel filled with this gas, and the mouth covered with a piece of paper, a circulat ing white vapour will arise in a few se conds, which will soon be followed by an explosion with flame.
For the rest of its properties, see MU. RIATIC OXYGLVIZED ACID, NITRIC ACID GAS, and NITRIC acid.
GAS, nitric oxide, or NITROUS GAS. We owe our first knowledge of this elastic fluid to Dr. Priestley, who called it nitrous air. It may be formed by passing ammo niacal gas through the black oxide of man ganese, heated red hot in an earthen tube ; but it is most easily obtained by abtract ing a portion of its oxygen from nitric acid. For this purpose fine copper wire, or copper filings, may be put into a re tort, with an equal weight of nitric acid, di luted with four or five parts of water, and moderate heat applied; or diluted only with an equal quantity of water, and no heat employed. After the atmospheric air is expelled from the retort, the gas that comes over may be received in the pneumatic apparatus. Other metals might be employed for the same purpose, but mercury and copper appear to afford it in the greatest purity ; and the latter is per haps preferable, because the process goes on more regularly with it.
This gas is colourless, and somewhat heavier than atmospheric air. It is ex tremely deleterious, killing even insects very quickly, and destroying plants. Wa ter deprived of air absorbs about one ninth of its bulk of this gas, without ac quiring any taste from it ; and a boiling heat expels it again unchanged. If the water contains air, the gas is partly de composed, and the absorption, though in reality greater, is apparently less, from the nitrogen evolved. Water impregnat ed with earthy salts,-does not absorb so much ; a solution of green sulphate, or green muriate of iron, however, abstirbs it rapidly, and becomes dark brown, and almost opaque. When this is effected over mercury, the gas may be expelled unchanged by a moderate heat, or by placing the solution in a vacuum, though perhaps not the whole of it. Solutions of nitrate of iron, the sulphates of tin, and of zinc, and muriate of zinc, likewise absorb it.