[1] Except where other units are given, the units throughout this
article are feet, pounds, pounds per sq. ft., feet per second.
[2] _Journal de M. Liouville_, t. xiii. (1868); _Mémoires de
l'Académie, des Sciences de l'Institut de France_, t. xxiii., xxiv.
(1877).
[3] The following theorem is taken from a paper by J. H. Cotterill,
"On the Distribution of Energy in a Mass of Fluid in Steady Motion,"
_Phil. Mag._, February 1876.
[4] The discharge per second varied from .461 to .665 cub. ft. in two
experiments. The coefficient .435 is derived from the mean value.
[5] "Formulae for the Flow of Water in Pipes," _Industries_
(Manchester, 1886).
[6] Boussinesq has shown that this mode of determining the corrective
factor [alpha] is not satisfactory.
[7] In general, because when the water leaves the turbine wheel it
ceases to act on the machine. If deflecting vanes or a whirlpool are
added to a turbine at the discharging side, then v1 may in part
depend on v2, and the statement above is no longer true.
HYDRAZINE (DIAMIDOGEN), N2H4 or H2 N·NH2, a compound of hydrogen and
nitrogen, first prepared by Th. Curtius in 1887 from diazo-acetic ester,
N2CH·CO2C2H5. This ester, which is obtained by the action of potassium
nitrate on the hydrochloride of amidoacetic ester, yields on hydrolysis
with hot concentrated potassium hydroxide an acid, which Curtius
regarded as C3H3N6(CO2H)3, but which A. Hantzsch and O. Silberrad
(_Ber._, 1900, 33, p. 58) showed to be C2H2N4(CO2H)2, bisdiazoacetic
acid. On digestion of its warm aqueous solution with warm dilute
sulphuric acid, hydrazine sulphate and oxalic acid are obtained. C. A.
Lobry de Bruyn (_Ber._, 1895, 28, p. 3085) prepared free hydrazine by
dissolving its hydrochloride in methyl alcohol and adding sodium
methylate; sodium chloride was precipitated and the residual liquid
afterwards fractionated under reduced pressure. It can also be prepared
by reducing potassium dinitrososulphonate in ice cold water by means of
sodium amalgam:--
KSO3 \ KSO3 \
> N·NO --> > N·NH2 --> K2SO4 + N2H4.
KO / H /
P. J. Schestakov (_J. Russ. Phys. Chem. Soc._, 1905, 37, p. 1) obtained
hydrazine by oxidizing urea with sodium hypochlorite in the presence of
benzaldehyde, which, by combining with the hydrazine, protected it from
oxidation. F. Raschig (German Patent 198307, 1908) obtained good yields
by oxidizing ammonia with sodium hypochlorite in solutions made viscous
with glue. Free hydrazine is a colourless liquid which boils at 113.5°
C., and solidifies about 0° C. to colourless crystals; it is heavier
than water, in which it dissolves with rise of temperature. It is
rapidly oxidized on exposure, is a strong reducing agent, and reacts
vigorously with the halogens. Under certain conditions it may be
oxidized to azoimide (A. W. Browne and F. F. Shetterly, _J. Amer. C.S._,
1908, p. 53). By fractional distillation of its aqueous solution
hydrazine hydrate N2H4·H2O (or perhaps H2N·NH3OH), a strong base, is
obtained, which precipitates the metals from solutions of copper and
silver salts at ordinary temperatures. It dissociates completely in a
vacuum at 143°, and when heated under atmospheric pressure to 183° it
decomposes into ammonia and nitrogen (A. Scott, _J. Chem. Soc._, 1904,
85, p. 913). The sulphate N2H4·H2SO4, crystallizes in tables which are
slightly soluble in cold water and readily soluble in hot water; it is
decomposed by heating above 250° C. with explosive evolution of gas and
liberation of sulphur. By the addition of barium chloride to the
sulphate, a solution of the hydrochloride is obtained, from which the
crystallized salt may be obtained on evaporation.
Many organic derivatives of hydrazine are known, the most important
being phenylhydrazine, which was discovered by Emil Fischer in 1877.
It can be best prepared by V. Meyer and Lecco's method (_Ber._, 1883,
16, p. 2976), which consists in reducing phenyldiazonium chloride in
concentrated hydrochloric acid solution with stannous chloride also
dissolved in concentrated hydrochloric acid. Phenylhydrazine is
liberated from the hydrochloride so obtained by adding sodium
hydroxide, the solution being then extracted with ether, the ether
distilled off, and the residual oil purified by distillation under
reduced pressure. Another method is due to E. Bamberger. The diazonium
chloride, by the addition of an alkaline sulphite, is converted into a
diazosulphonate, which is then reduced by zinc dust and acetic acid to
phenylhydrazine potassium sulphite. This salt is then hydrolysed by
heating it with hydrochloric acid--
C6H5N2Cl + K2SO3 = KCl + C6H5N2·SO3K,