KS03  N•NO .KS03~ N

NH2~KSO +N,H4 . KO~ 11,, so. e- so. a a• eg t o- ~• o w00 3000 Discharge - C.& per min . , Tip Speed . /00 ft. per sec . FIG . 213 . . woo 60o0 P . J . Schestakov (J . ;Riess . Phys . Chem .

Sec_; 1905, 37, p . 1:) solid

hydrocarbons, :all of high industrial value . For details obtained hydrazine by oxidizing urea with sodiumhypochlorite reference should be made to the articles wherein the above in the presence of benzaldehyde, which, by combining with the subjects are treated . From the chemical point of view the hydrazine, protected it from oxidation . F . Raschig (German hydrocarbons are of fundamental importance, and, on account Patent 108307, 1008) obtained good yields by oxidizing ammonia of their-great number, and still greater number of derivatives, with sodium hypochlorite in solutions made viscous with glue. they are studied as a separate branch of the science, namely, Free hydrazine is a colourless liquid which boils at r 13.5° C., organic chemistry: and solidifies about o° C. to colourless crystals; it is heavier See CHEMISTRY for an account of their classification, &c . than water, in which it dissolves with rise of temperature . It HYDROCELE (Gr . Mop, water, and KriXti, tumour), the is rapidly oxidized on exposure, is a strong reducing agent, and medical term for any collection of fluid other than pus or blood reacts vigorously with the halogens . Under certain conditions in the neighbourhood of the testis or cord . The fluidis usually it may be oxidized to azoimide (A . W .

Browne and F . F. serous Hydrocele may be congenital or arise in the middle-aged Shetterly, J . Amer . C.S., 1908, p . By fractional distilla- without apparent cause, but it is usually associated with chronic tion of its aqueous solution hydrazine hydrate N2Hs•H2O orchitis or with tertiary syphilitic enlargements . Thehydrocele (or perhaps H2N.NH2OH), a 'strong base, is obtained, which appears as a rounded; fluctuating translucent swelling in the precipitates the metals from solutions of copper and silver scrotum, and when greatly distended causes a dragging pain; salts at ordinary temperatures . It dissociates completely in a Palliative treatment consists in tapping aseptically and removvacuum at 143°, and when heated under atmospheric pressure ing the, fluid, the patient afterwards wearing a suspender; to 183° it decomposes into ammonia and nitrogen (A . Scott, The condition frequently recurs and necessitates radical J . Chem . Soc., 1904, 85, p . 913) . The sulphate N2H4•H2SO4, treatment .

Various substances may be injected; or the crystallizes in tables which are slightly soluble in

cold water hydrocele is incised,' the tunica partly removed and the cavity and readily soluble in hot water; it is decomposed by heating drained . ' above 250° C. with explosive evolution of gas and liberation of HYDROCEPHALUS (Gr. ii&ap, water, and Ke4aXii, head), sulphur . By the addition of barium chloride to the sulphate, a a term applied to disease of the brain which is attended solution of the hydrochloride is obtained, from which the with excessive effusion of fluid into its cavities . It exists crystallized salt may be obtained on evaporation. in two forms—acute and chronic hydrocephalus . Acute hydro- Many organic derivatives of hydrazine are known, the most cephalus is another name for tuberculous meningitis (see important being phenylhydrazine, which was discovered by Emil MENINGITIS) . Fischer in 1877 . It can be best prepared by V . Meyer and Lecco's Chronic hydrocephalus, or " water on the brain," consists in method (Bet., 1883, 16, p . 2976), which consists in reducing phenyl- an effusion' of fluid into the lateral ventricles of the brain . It diazonium chloride in concentrated";hydrochloric acid, solution with is not preceded by tuberculous deposit or acute inflammation, stannous chloride also dissolved in concentrated hydrochloric acid . Phenylhydrazine is liberated from the hydrochloride so obtained but depends' upon congenital malformation or upon chronic by adding sodium hydroxide, the solution being then extracted with inflammatory changes affecting the membranes . When the ether, the ether distilled off, and the residual oil purified by distilla- disease is congenital, its presence in the foetus is-apt to be a source non under reduced pressure .

Another method is due to E,

Balm- of difficulty in parturition . It is however more commonly Berger . The diazonium chloride, bythe addition of an alkaliee developed in' the first six months of life; but it occasionally sulphite, is converted into a diazosulphonate, which is then reduced by zinc dust and acetic acid to phenylhydrazine potassium sulphite. arises in older children, or even in adults . The chief symptom This salt is then hydrolysed by heating it with hydrochloric arid— is the gradual increase in size of the upper part of the head out of all propoftion to the face or the rest of the body . Occurring at an age when as yet the bones of the skull have not become welded together, the enlargement may go on to an enormous extent, the spaces betweehthe bones becoming more and more expanded.' In a well-marked•case the deformity is very striking; the tippet part of the forehead projects abnormally, and the (see ALDEHYDES, KETONES and SUGARS) . It is a strong reducing agent; it precipitates cuprous oxide when heated ,with Fehling's solution, nitrogen and benzene being formed at the same ding—C,H5.NH•NH2+2CuO =Cu,O+Ns+H20+C6Hs . Byenergetic 'reductign of phenylhydrazine (e.g. by use of ziec dust and.hydrochloric acid), ammonia and aniline are produced•-C6H,N`I'l•NHs + 2H = C;H,NH, + NH, . It is also a most important synthetic reagent . I t combines with aceto-acetic ester to form phenylmethylpyrazolone; from which antipyrine (q.v.) may be obtained . Indoles (q.v.) are formed by heating certain hydrazones with anhydrous zinc chloride; while semicarbazides, pyrrols (q.v.) and many other types of organic compounds may be synthesized by the use of suitable phenylhydrazine derivatives .