UREA

(Lat.), n. f. U2r(ur)-e(a)'a3. From otpov, urine. Fr., uree. Ger., Harnstoff. Carbamide, or carboxyl diamine, CON2H4 = C I NH2)., (or H2N (CO) NH2), the chief solid constituent of the urine and the principal excretory product containing nitrogen. It forms long, colorle , prismatic crystals, melting at 130 C., soluble in water and moderately soluble in alcohol. It acts as a base, forming addition compounds with acids and their salts and with metallic oxides. It is decomposed by heat and moisture, and more slowly by the action of an organized ferment (Micrococcus ureas), into normal ammonium carbonate. This proce takes place in the urine, constituting its so-called alkaline fermentation and giving to stale urine its peculiar strong ammoniacal odor. U. is also decomposed into cyanogen compounds (cyanuric acid and ammelide) by the action of dry neat. It is remarkable as being the first organic body that was prepared artificially, WShler having accomplished this in 1828 by making the isomeric cyanate of ammonium, and then transforming the latter into u. by evaporation. [B.] Mesoxalyl u. See ALLOXAN. U. and mercury nitrate. An addition compound of varying composition formed by the action of mercuric nitrate on u. [B.] U. argentic oxide. Ger., Harnstoffsilberoxyd. A grayish granular substance, 2CON2H4.3Ag8O. [B.] U. cyanurate. See TETRURET. U. hydrochloride. A deliquescent crystalline ma , CON2H4.HC1= H2N CO NH3C1, formed by the action of dry hydrochloric-acid gas on u. [B.] U. mercuric oxide. Ger., Harnstoffquecksilberoxyd. 1. A white crystalline powder, CON2H4.HgO. 2. A gelatinous substance, 2CON2H4.3HgO. 3. The compound CON2H4.2HgO. [B.] U. nitrate. A substance, CON2H4.HNO3 = H2N (CO) NSHONO4, forming tabular crystals on the addition of nitric acid to a solution of u. (concentrated urine). [B.] U. oxalate. A substance, 2CON2- H4.H2C2O4 + 2HO = H2N CO NHSOC2O2.OH N CO NH2 + H2O, forming laminar crystals, and produced?by the action of oxalic acid on a rather concentrated solution of u. [B.] U. sodiochloride. A substance, CON2H4.NaCl + H2O, obtained as a crystalline body by evaporating a solution containing both u. and sodium chloride urine. [B.] [s. 676]