HYDRAZINE, or DIAMIDOGEN," a substance having the formula Nsli, (or ILN. NH,), obtained (together with oxalic acid, H2C304,) by heating an aqueous solution of the complicated substance known as triazoacetic acid (CsHaN.),(COOH)s. It is a gas with a peculiar penetrating odor, but the properties of the pure substance are imperfectly known, on account of the avidity with which it combines with water to form the hydrate, N,H.H.0, and the consequent difficulty of isolating it. Hy drazine hydrate is a powerful base, combining with acids to produce numerous definite crystal line salts. Among these the sulphate, N2114. H.SO4, and the two hydrochlorides, N,H.2HC1 and N2H4.HC1, are important. The hydrate may be prepared by boiling the sulphate with a solu tion of caustic It is a fuming liquid, somewhat oily in appearance, and boiling at 245° F. The hydrate reduces cold ammoinacal solutions of silver nitrate and also reduces Fehling's solution. It attacks glass, cork and india rubber, but may be kept in silver vessels.
The substances derived from hydrazine by replacing one or more of its hydrogen atoms by compound radicals are also called ((hydra miles?' If only one hydrogen atom is replaced the hydrazine is said to be "primary?' If two hydrogen atoms are replaced, the hydrazine is said to be The radical which re places the hydrogen may belong to the fatty series, or to the aromatic series. One or more
of the hydrogen atoms may also be replaced by a metal, such as sodium. The most important of the organic hydrazines is phenylhydrazine, in which one of the hydrogen atoms is replaced by the aromatic radical phenyl, C.H,. This sub stance, which has the formula is a colorless, oily liquid, which solidifies a mass of tabular monoclinic crystals on cooling to 73° F. It mixes with alcohol, ether, benzene and chloroform, but hardly at all with water. It re duces Fehling's solution in the cold, and is very poisonous. A secondary hydrazine is metrical)) when the two substituted radicals are attached to different nitrogen atoms; it is if they are attached to the same nitrogen atom. Thus (C,H5)HN.NH (C211.) is the symmetrical secondary hydrazine of phenyl (C.H.) and ethyl (Ca.). while (Gala) (C2Ho) N.NH, is the unsymmetrical sec ondary hydrazine of the same radicals.