GASEOUS OXYD OF NITROGEN; OR

NITROUS OXYD.

PART XXVI.

THE combination of nitrogen and oxygen, which we considered before under the name of nitrous gas, does not constitute the first degree of oxygenation of nitrogen ; there is another degree below this. This combination was formerly called dephlogisticated nitrous gas, but now gaseous oxyd of nitrogen, or nitrous oxyd. It was first discovered by Priestley. Its nature and properties have since been investigated (though not very accurately) by a society of Dutch chemists.

Professor Davy has examined with uncommon accuracy the formation and properties of all the substances concerned in its production. He has detected the sources of error in the experiments of Priestley and the Dutch chemists, and to him we are indebted for a thorough knowledge of this gas. We shall therefore exhibit the philosophy of this gaseous fluid as we find it in his researches concerning the nitrous oxyd.

SECT. I.

PROPERTIES OF GASEOUS OXYD OF
NITROGEN.

GASEOUS oxyd of nitrogen exists in the form of permanent gas. A candle burns with a brilliant flame and crackling noise in it; before its extinction the white inner flame becomes surrounded with a blue one.

Phosphorus introduced into it, in a state of actual inflammation, burns with increased splendour, as in oxygen gas. Sulphur introduced into it when burning with a feeble blue flame is instantly extinguished; but when in a state of vivid inflammation, it burns with a rose-coloured flame. Ignited charcoal burns in it more brilliantly than in atmospheric air. Iron wire, with a small piece of wood affixed to it when inflamed, and introduced into a vessel filled with this gas, burns vehemently, and throws out bright scintillating sparks. No combustible body however burns in it unless it be previously brought to a state of vivid inflammation. Hence sulphur may be melted, and even sublimed in it; phosphorus may be liquefied in it without undergoing combustion. Nitrous oxyd is pretty rapidly absorbed by water that has been boiled; a quantity of gas equal to rather more than half the bulk of the water may be thus made to disappear; the water acquires a sweetish taste, but its other properties do not differ perceptibly from common water. The whole of the gas may be expelled again by heat. It does not change blue vegetable colours. It has a distinctly sweet taste, and a faint but agreeable odour. It undergoes no diminution when mingled with oxygen or nitrous gas. Most of the liquid inflammable bodies, such as ether, alcohol, volatile and fat oils, absorb it rapidly and in great quantity. Acids exert but little action on it. The affinity of the neutrosaline solutions for gaseous oxyd of nitrogen is very feeble. Green muriate and green sulphate of iron, whether holding nitrous gas in solution or not, do not act upon it. None of the gases, when mingled with it, suffer any perceptible change at common temperatures; the muriatic and sulphureous acid gases excepted, which undergo a slight expansion. Alkalics freed from carbonic acid exposed in the dry or solid form have no action upon it; they may however be made to combine with it in the nascent state, and then constitute saline compounds of a peculiar nature. These combinations deflagrate when heated with charcoal, and are decomposed by acids; the gaseous oxyd of nitrogen being disengaged. It undergoes no change whatever from the simple effect of light. The action of the electric spark for a long while continued, converts it into a gas analogous to atmospheric air and nitrous acid; the same is the case when it is made to pass

through an ignited earthen tube. It explodes with hydrogen in a variety of proportions at very high temperatures; for instance, when electric sparks are made to pass through the mixture. Sulphurated hydrogen, heavy and light carbonated hydrogen gases, and gaseous oxyd of carbon, likewise burn with it when a red heat is applied. 100 parts by weight of nitrous oxyd contain 36.7 of oxygen and 63.3 of nitrogen; 100 cubic inches weigh 50 grains at 55° temperature and 30 atmospheric pressure. Animals when wholly confined in gaseous oxyd of nitrogen give no signs of uneasiness for some moments, but they soon become restless and die. When gaseous oxyd of nitrogen is mingled with atmospheric air, and then received into the lungs, it generates highly pleasurable sensations; the effects it produces on the animal system are eminently distinguished from every other chemical agent. It excites every fibre to action, and rouses the faculties of the mind, inducing a state of great exhilaration, an irresistible propensity to laughter, a rapid flow of vivid ideas, and unusual vigour and fitness for muscular exertions, in some respects resembling those attendant on the pleasantest period of intoxication, without any subsequent languor, depression of nervous energy, or disagreeable feelings; but more generally followed by vigour, and a pleasurable disposition to exertion, which gradually subsides.

Such are the properties which characterize the nitrous oxyd.

The Dutch chemists and some French and German philosophers assert* that it cannot be respired; that burning phosphorus, sulphur, and charcoal, are extinguished in it, &c. It is probable they did not examine it in a state of purity, for it is otherwise difficult to account for these and many other erroneous opinions.

METHODS OF OBTAINING GASEOUS OXYD OF NITROGEN.

Gaseous oxyd of nitrogen is produced when substances having a strong affinity with oxygen are brought into

Gren's Principles of Chemistry, 1800. Scherer's Introduction to the Knowledge of Gaseous Bodies, 1801.

It may

contact with nitric acid, or with nitrous gas. therefore be obtained by various processes, in which nitrous gas or nitric acid is decomposed by substances capable of attracting the greater part of their oxygen. The most commodious and expeditious, as well as the cheapest mode of obtaining it, is by decomposing nitrate of ammonia, at a certain temperature, in the following

manner.

1. Introduce into a glass retort some nitrate of ammonia, and apply the heat of an Argand's lamp; the salt will soon liquefy, and when it begins to boil, gas will be evolved. Increase the heat gradually till the body and neck of the retort become filled with a semi-transparent milkywhite vapour. In this state the temperature of the fused nitrate is between 340° and 480°. After the decomposition has proceeded for a few minutes, so that the gas evolved quickly enlarges the flame of a taper held near the orifice of the retort, it may be collected over water, care being taken during the whole process never to suffer the temperature of the fused nitrate to rise above 500° Fahr. which may be easily judged of, from the density of the vapours in the retort, and from the quiet ebullition of the fused nitrate; for if the heat be increased beyond this point the vapours in the retort acquire a reddish and more transparent appearance; and the fused nitrate begins to rise, and occupy twice the bulk it did before. The nitrous oxyd after its generation is allowed to stand over water for at least six hours, and is then fit for respiration or other experiments. (See Appendix No. 26.)

RATIONALE....Nitrate of ammonia consists of nitric acid and ammonia; nitric acid is composed of nitrous gas and oxygen; and ammonia consists of hydrogen and nitrogen. At a temperature of about 480° the attractions of hydrogen for nitrogen in ammonia, and that of nitrous gas for oxygen in nitric acid, are diminished; while, on the contrary, the attractions of the hydrogen of ammonia for the oxygen of the nitric acid, and that of the remaining nitrogen of the ammonia for the nitrous gas of the nitric acid, are increased: hence all the former affinities are broken, and new ones produced, namely; the hydrogen of the ammonia attracts the oxygen of the nitric acid, the result of which is water; the nitrogen of the ammonia combines with the liberated nitrous gas, and forms nitrous

oxyd. The water and nitrous oxyd produced probably exist in binary combination in the aeriform state at the temperature of the decomposition.

Such is the philosophy of the production of gaseous oxyd of nitrogen, by decomposing nitrate of ammonia at that temperature, given by Davy.

To illustrate this complicated play of affinity more fully, the following sketch may not be deemed superfluous.

DIAGRAM,

REMARK.... Professor Davy has likewise pointed out, that when the heat employed for decomposing nitrate of ammonia is raised above the before-stated temperature, another play of affinities takes place; the attractions of nitrogen and hydrogen for each other, and of oxygen for nitrous gas, are still more diminished, whilst that of nitrogen for nitrous gas is totally destroyed, and that of hydro