Nitrites, salts produced by the union of nitrous acid with bases; general formula, MNOa. The principal metallic salts are those of potassium, sodium, barium, ammonium, cop-lead, and nickel. The nitrites of lead form an interesting series, but are of more professional than general interest; and the same remark applies to the double potassium nitrites with other metals. The nitrites are usually prepared by reducing the nitrates. Nitrite of potassium and of soda may be obtained by decomposing potassic nitrate at a red heat, dissolving the residue in water, crystallizing out the remaining nitrate, and evaporating. - The alcoholic nitrites, or nitrous ethers, are bodies of great interest, to the physiologist as well as chemist. The principal are the nitrites of amyl, ethyl, methyl, and butyl. The nitrite of amyl (C5H11NO2) is an inflammable liquid, of a fruity pear-like odor, reddish yellow color, and specific gravity 0.877, boiling at 196°. It may be prepared by passing nitrous vapors into amylic alcohol in a gently heated retort, rectifying the distillate, and collecting those portions going over at 196°. When inhaled it acts as a powerful stimulant to the heart, the excitement being followed by greatly diminished power of the organ and contraction of the external vessels.

It suspends the respiration of animals, but the effect may be stopped short of death, the result being a state resembling trance. The appearance after death differs with the mode of administration. If the nitrite is given rapidly, the lungs and brain are found free from congestion, and the left side of the heart empty, but the right cavities will be engorged. When administered slowly, the lungs and brain are congested and both sides of the heart contain blood. Nitrite of ethyl, or nitrous ether, C2H5N02 (formerly called nitric ether, saltpetre, and naphtha), was first observed by Rumkel in 1681, but its composition was first exactly determined by Dumas and Boullay. It is prepared by distilling a mixture of equal parts of alcohol and nitric acid, a gentle heat being applied at the commencement. The distillate is received in a series of Woulf's bottles half filled with salt water. The nitrous ether collects on the surface of the brine. It is a yellowish liquid, having the odor of apples, sparingly soluble in water, but perfectly so in all proportions in alcohol. It boils at 62°, and has a specific gravity of 0.947. It is decomposed by the action of caustic potash into nitrite of potassium and alcohol.

The sweet spirits of nitre of pharmacy is a solution of nitrous ether, aldehyde, and several other substances, prepared by distilling 3 lbs. of alcohol with 4 lbs. of nitric acid. Nitrite of methyl (CH3NO2) is prepared by treating wood spirit with nitric acid and copper turnings. When a liquid, it has a specific gravity of 0.991, and boils at 11° F. Its smell resembles that of nitrous ether. Nitrite of butyl (C4H9NO2) has been employed by Tyndall with advantage in experiments upon polarized light.