Hydraulics
that part of mechanical science which has to do with conducting, raising, and confining water or supplying it as a motive power. It is sometimes called hydro-mechanics, and is subdivided into hydrostatics and hydrodynamics.
HYDRAZINES (hidrä-zīns), in chemistry, H2N-NH2. Hydrazine is not known in a free state. Its derivatives are obtained by the reduction of nitrosoamines by zinc dust and acetic acid, (CH3)2N: NO + 4H' (dimethyl-nitrosomine = (CH3)2N-NH2 + HOH (dimethylhydrazine); also formed by the action of nascent hydrogen on nitrosodiethyl urea and diethyl hydrazine urea.