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 EDDIO:METER.
When 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 oxygenation, as some had supposed.
GAS, nitrous oxide. This is the gaseous oxide of nitrogen, or of azote of some ; 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 leave it dry and compact. The latter at a heat between 275° and 300° sublimes without being decomposed ; at 320° it becomes fluid, and is partly decomposed, partly sublimed: between 340° and 480° it is decomposed rapidly. The fibrous is not decomposed below 400°, but a heat above 450° decomposes it ; at 600° a lumi nous appearance is produced in the retort, and nitric oxide, nitrous oxide, and nitro gen, mixed in various proportions, are evolved; at 700° or 800° an explosion takes place. It is best to perform the opera tion over an Argand's lamp, as the heat may thus be brought to the requisite de gree speedily, and kept from going too far. It should be received over water, and suffered to stand an hour in contact with it, to free it from any nitrate of am monia that may have been sublimed, as well as from any acid suspended in it. Dr. Pfaff recommends mixing very pure sand with the nitrate, to prevent the hazard of explosion ; and observes, that it is particularly requisite it should not be contaminated with muriatic acid. One
pound of the compact nitrate, yields 4.25 cubic feet of gas, and a pound of the fibrous nearly five cubic feet.
The most singular property of this gas is its action on the animal system. Dr. Priestley had found that it was fatal to animals confined in it. Mr. Davy first ventured to respire it, which he did to considerable extent. When breathed alone for a minute or two, and some have gone so far as four or five minutes, it generally produces a pleasant thrilling, .4particularly in the chest and extremities, frequently with an inclination to laugh, sometimes an irresistible propensity to gesticulation and muscular exertion.
mind meanwhile is often totally ab stracted from all surrounding objects. Sometimes its effects are not entirely (Es . sipated for some hours; and it is remark able, that, however strong they may have been, no sense of debility or langour is in duced after they have subsided. On a few individuals, however, its effects have been ' unpleasant and depressing; in some it has produced convulsions, and other ner vous symptoms; and on some it has had no sensible effect. Indeed, not only dif ferent persons, but the same ii.dividual, will be variously affected by it, perhaps, at different times. Similar effects have been produced on those who have tried it abroad.
In debility, arising from residence in a hot climate, and intense application to business, this gas has proved a comp/ete• • remedy. It has given voluntary power over palsied parts while inhaled, and the subsequent application of other remedies has effected a cure. Dr. Pfaff has sug gested its use in melancholia : but in some cases of this disease it has done no good, and in one harm.
GAS, nitrogen or azotic. Under the article ATMOSPHERE it has been observ ed, that about three fourths of our at mosphere consist of gas, unfit to main. tam combustion, or support life. It is called nitrogen or azotic gas, and is a little lighter than atmospheric air. It is incapable of supporting life, or combus tion, yet a small portion is absorbed in respiration. It is not inflammable, though it unites with oxygen in different propor tions, forming nitrous oxide, when the oxygen is only .37, nitric oxide when it is .56, and nitric acid when .705. It is one of the most general elements of ani mal substances. With hydrogen it forms ammonia ; and Fourcroy suggested, that it might possibly be the alkaligenating principle, though he confesses there are no facts in support of this conjecture ; the name of alkaligen, therefore, which has been proposed for it, is certainly in admissible. It dissolves small portions of phosphorus, sulphur, and carbon.