GAS. 



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 OXYGEXIZED ACID, NlTRIC 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 retort, 

 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, absorbs 

 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. 



Nitrous gas has no acid properties. 

 It does not redden vegetable colours, 

 but impairs them. It extinguishes the 

 flame of a candle, or burning sulphur, 

 and the phosphoric light of animal sub- 

 stances : but lighted charcoal continues 

 to burn in it ; lighted phosphorus burns 

 in it with great splendour, though, if not 

 previously kindled, it may be melted or 

 sublimed in it, without taking fire ; and 

 Homberg's pyrophorus kindles in it spon- 

 taneously. Its most important property 

 is its affinity for oxygen gas, on account 

 of which it was employed by Dr. Priest- 

 ley, as it still is by many, to ascertain the 

 quantity contained in atmospheric air. 

 See EUDIOMETER. 



Wlven mixed with oxygen gas, red 

 fumes arise, heat is evolved, and the two 

 gases, if in due proportion and both pure, 

 disappear, being converted into nitric 

 acid. 



This gas is soluble in nitric aaid, and 

 alters its properties in some measure, 

 without, however, converting it into an 

 acid, in a distinct state of oxyge nation, as 

 some had supposed. 



GAS, nitrous oxide. This is the gaseous 

 oxide of nitrogen, or of azote of some ; a 

 compound of nitrogen with a still less 

 proportion of oxygen than the preceding 

 gas. It is not to be obtained certainly, 

 with any purity, but by the decomposi- 

 tion of nitrate of ammonia. For this pur- 

 pose, nitric acid, diluted with five or six 

 parts of water, may be saturated with 

 carbonate of ammonia, and the solution 

 be evaporated by a very gentle heat, add- 

 ing occasionally a little of the carbonate, 

 to supply what is carried off. The nitrate 

 crystallizes in a fibrous mass, unless the 

 evaporation has been carried so far as to 



