492 PRACTICAL ORGANIC CHEMISTRY concentrated sulphuric acid and the nitrogen thereby converted quantitatively to ammonium sulphate. The acid solution is then transferred to a steam-distillation apparatus, made alkaline and the ammonia steam-distilled into saturated boric acid solution and finally titrated against standard acid. The more easily the nitrogen is converted to ammonia, the more satisfactorily can the method be carried out. This method was originally utilised for the determination of nitrogen in amines, amino-acids, etc., and was particularly useful for the nitrogen analysis of biological material. The sulphuric acid digestion may be expedited and improved by the use of catalysts such as selenium and mercuric sulphate. The direct method is unsuitable for a number of substances, especially azo compounds and substances where oxygen is attached to nitrogen as in nitro and nitroso compounds, as there is a tendency to lose some of the nitrogen as gaseous nitrogen or as an oxide. Such compounds
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.