Protoxide of nitrogen is a transparent, colorless gas, with a sweetish taste and smell. It is much more soluble in cold than in hot water, and therefore should be collected over the latter. Under a pressure of 50 atmospheres at 45° it is reduced to a colorless liquid, and it may be frozen into a transparent solid at about — 150°. This gas is about half as heavy again as atmospheric air, its specific gravity being 1.527. It supports the com bustion of many bodies, such as carbon, sulphur, phosphorus, and iron, with a bril liancy similar to that which they exhibit in oxygen; and, like oxygen. when mixed with hydrogen, it forms a mixture which explodes on the application of a flame. The most remarkable property of the gas is its intoxicating power on the animal system. It may be respired for a short time if quite pure, or if only mixed with atmospheric air, without danger or serious inconvenience. The intoxication is frequently accompanied with an irresistible propensity to muscular exertion, and usually with uucontrollabie bursts of laughter, and hence the gas has received the name of laughing gas. It is best obtained by heating solid nitrate of ammonia in a glass retort, when it is converted into protoxide of nitrogen and water. It has recently come into frequent use as an anaesthetic in den tistry and similar cases. It is less suited to protracted operations, as the effects are transient. It produces much less disturbance of the system than chloroform.
B1,120.1ide of nitrogen is a colorless gas, very slightly soluble in water, and having a specific gravity of 1.039. Its taste and smell (if any) are unknown, since, in the pres ence of atmospheric air, it instantly becomes more highly oxidized, and forms yellowish red fumes of hypouitric acid. As it is of little importance, it is unnecessary here to describe the mode of obtaining it.
.Nitrous acid, or nitrous anhydride, is a substance of which, in its uncombined state, very little is yet known further than that it is a dark-blue, very volatile fluid, which boils at 32°, and is then converted into an orange-red gas.
Hyponitric acid presents a remarkable example of a body within comparatively small limits of temperature, occurring in a solid, a fluid, and a gaseous form. At a tempera ture of —4° it occurs in the form of colorless prismatic crystals, which are converted at about into a fluid which, till the temperature reaches about 30°, is colorless; but at a higher temperature becomes yellow and orange, and at about 82° boils, arid is converted into a brownish-red vapor. It is chiefly the vapor of hyponitric acid that forms the
n fumes that are produced when hinoiale of nitrogen comes in contact with the air. It possesses a very disagreeable suffocating odor, and a caustic action, and colors the skin yellow, like nitric acid. It does not enter into combination with bases but is immediately decomposed by them into nitric and nitrous acids; and it is in consequence of its not possessing this essential character of an acid that Graham has given it the name of peroxide of nitrogen, a term that has since been adopted by Miller and other chemists.
_Nitric acid is described in a special article.
Nitrogen combines with hydrogen in four proportions, but none of these compounds can be formed by the direct union of the component elements, and only one of them, viz., ammonia, has been obtained in the isolated form. They are—imidogen (NH), amido Igen (NIL), ammonia (NH,), and ammonium (NII,). Of these, the first two will be noticed under ORGANIC BASES, while the last two are sufficiently described under Ammoxia.
Nitrogen combines with chlorine, bromine, and iodine. The chloride of nitrogen is a heavy, oily, orange-colored fluid, insoluble in water, and evolving a vapor of a highly irritating nature. It is one of the most dangerous compounds known in chemistry, as it explodes with extreme violence when brought in contact with phosphorus, arse nic, potash, ammonia, caoutcbouc, numerous oily matters, etc., at ordinary temperatures, and spontaneously when heated to above 200°. It has occasioned so many serious acci dents that we shall omit all details regarding its mode of preparation. Its exact for mula is unknown. Bromide of nitrogen is an oily-looking detonating liquid, resembling the chloride in appearance and properties. Iodide of nitrogen occurs as a black powder, which when dry explodes upon the slightest touch, and often without assignable cause.
Nitrogen enters into combination with various metals, as mercury, copper, titanium, molybdenum, and vanadium, forming a class of compounds to which the term nitrides is applied. Thew most marked characteristic is that, like the preceding set of Com pornds, they are highly explosive, resolving themselves when struck, or at a high tem perature, into their constituent elements.