. Elements of human physiology. Physiology. 436 PHYSIOLOGY The reaction may be represented as follows /NH., \nh., CO / NH., CO \nh \nh. On further heating cyanuric acid C3H3N3O3 is formed. Urea may be formed from ammonium cyanate, with which it is isomeric, by simply heating with water. On exposure to the air urine becomes strongly alkaline, and smells of ammonia. At the same time the earthy phos- phates are precipitated. This change (which may be prevented by boiling the urine in a flask, the neck of which is closed by cotton wool) is due to infection of the urine by a micro- organism, Microc
. Elements of human physiology. Physiology. 436 PHYSIOLOGY The reaction may be represented as follows /NH., \nh., CO / NH., CO \nh \nh. On further heating cyanuric acid C3H3N3O3 is formed. Urea may be formed from ammonium cyanate, with which it is isomeric, by simply heating with water. On exposure to the air urine becomes strongly alkaline, and smells of ammonia. At the same time the earthy phos- phates are precipitated. This change (which may be prevented by boiling the urine in a flask, the neck of which is closed by cotton wool) is due to infection of the urine by a micro- organism, Micrococcus urecB. Under the influence of this Fig. Urea nitrate. Urea oxalate. organism the urea undergoes hydration, taking up two mole- cules of water and being converted into ammonium carbonate. /NH., /ONH^ CO; "+2H„o = coC \NH, Urea \onh/ Ammoniuui carbonate On treatment with an alkaline hypobromite it is de- composed with the formation of free nitrogen and carbon dioxide: CO(NH.,).,-H3NaBrO = C0, + N, + 3NaBr 4-2H,0. This reaction is taken advantage of in the quantitative estimation of urea. 5 of urine are treated in a closed vessel with about 20 of alkaline sodium hypobromite solution. The CO2 produced is dissolved by the excess of alkali present, and the nitrogen is collected in a graduated cylinder. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Starling, Ernest Henry, 1866-1927. Chicago : W. T. Keener
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